Quick Reference

• What it is: The informal name for a tornado-prone corridor running from north Texas through Oklahoma, Kansas, and Nebraska, with secondary lobes into the Dakotas, Iowa, and Missouri.
• Term origin: Coined in 1952 by Air Force meteorologists Ernest J. Fawbush and Robert C. Miller, the same team that issued the first official tornado warning four years earlier.
• Most tornadoes by absolute count: Texas, averaging 155 a year. Per square mile: Kansas, with 4.4 tornadoes per 100 square miles.
• Peak month: May, with a national average of 269 tornadoes. April produces the most violent (EF4+) tornadoes.
• Worst single tornado on record: The Tri-State Tornado of March 18, 1925. 219 miles, 695 deaths, three states.
• The shift: Peer-reviewed research finds tornado activity has shifted 400 to 500 miles east since the 1950s, with strong tornadoes more than doubling in Dixie Alley since 1990.

Two Air Force meteorologists named the region in 1952 after they had already done the harder work, issuing the first official tornado warning in modern history four years earlier. Today, Tornado Alley is shorthand for the part of the country where warm Gulf air, cold Rocky Mountain air, and a fast-moving jet stream collide often enough to make tornadoes a fact of life. The lines on the map are not official, the boundaries are debated, and the alley itself is moving east. This is what Tornado Alley is, where it sits, why it forms, and what the data shows about where it is heading.

Where Did the Term “Tornado Alley” Come From?

The phrase was coined in 1952 by U.S. Air Force Major Ernest J. Fawbush and Captain Robert C. Miller as the title of a research project on severe weather over Texas and Oklahoma. Fawbush and Miller were already credited with issuing the first official tornado warning, on March 25, 1948, after correctly forecasting a tornado that hit Tinker Air Force Base in Oklahoma City. Their 1952 paper drew a north-south corridor from Lubbock, Texas, through Colorado and Nebraska. The phrase entered the public vocabulary on May 26, 1957, when the New York Times ran “Tornado Alley” as a headline. It has remained an informal, unofficial term ever since, more useful in conversation and on weather TV than in NOAA classification.

Where Tornado Alley Is, on a Map

The classic Tornado Alley footprint runs north and south through the Great Plains. Most climatologies put the core in northern Texas, Oklahoma, Kansas, and Nebraska. Broader definitions stretch the alley into South Dakota, Iowa, Missouri, Illinois, Indiana, western Ohio, and southern Minnesota. The terrain is what makes the map. From the Texas Panhandle to the upper Midwest, the land is flat to gently rolling with no mountain barriers, which means competing air masses meet without obstruction. On a weather map, the alley reads as a wide vertical band sitting east of the Rockies and west of the Mississippi River.

Why Tornado Alley Exists: The Geography of Formation

Tornadoes need three ingredients in the same place at the same time: warm moist air at the surface, cold dry air aloft, and strong wind shear. Tornado Alley delivers all three at once for a few months a year. Warm, humid air pushes north from the Gulf of Mexico. Cold, dry air slides off the Rocky Mountains and out of the Canadian Arctic. The flat plains let the two air masses run straight at each other with no terrain to break them up. The polar jet stream, a ribbon of fast-moving air five miles up, dips south in spring, adding upper-level wind that twists the rising convective columns into rotation. When a lifting trigger arrives, a dry line, a cold front, or a low-pressure center, the result is a supercell. A supercell that survives long enough becomes a tornado.

For background on the broader climate drivers behind these spring patterns, see our explainers on what El Nino is and what La Nina is.

The Top 10 States by Annual Tornado Count

Per NOAA Storm Prediction Center annual averages from the historical record:

1. Texas, 155 tornadoes a year. Largest absolute count in the country and largest land area, which puts the per-square-mile rate lower than its raw lead suggests.

2. Kansas, 96 tornadoes a year. Tornado Alley’s per-square-mile leader at about 4.4 tornadoes per 100 square miles. Kansas also produces about four times more strong (EF3 or higher) tornadoes per square mile than Florida.

3. Florida, 66 tornadoes a year. Outside classic Tornado Alley but high in raw count due to landfalling tropical systems and afternoon Gulf-fed storms. Most are weak EF0 or EF1.

4. Oklahoma, 62 tornadoes a year. The historical heart of violent-tornado country. Oklahoma has produced more EF4 and EF5 tornadoes per square mile than any other state over the long record.

5. Nebraska, 57 tornadoes a year. Northern reach of the classic alley.

6. Iowa, 51 tornadoes a year. Outbreak country in late May and June.

7. Missouri, 45 tornadoes a year.

8. Minnesota, 45 tornadoes a year.

9. Mississippi, about 40 tornadoes a year on a long-run basis, climbing fast as the alley shifts east.

10. Illinois, about 35 tornadoes a year, also rising.

For how these state-level numbers fit a broader weather-risk picture, see our companion piece on the 10 worst weather states.

Peak Season: April, May, and June

Tornado season builds and recedes with the jet stream. National averages by month per NOAA SPC: April produces about 190 tornadoes, May produces 269 (the peak), and June produces 191. April is also when violent tornadoes are most common, even though May runs a higher total. The geographic progression follows the moisture. In late March and April, the action is concentrated over the southern Plains, Oklahoma, north Texas, and Kansas. By late May and June, the threat shifts north into Nebraska, Iowa, the Dakotas, and the Midwest. Weaker EF0 and EF1 tornadoes dominate the late-season totals as the jet stream retreats toward Canada.

Historic Tornadoes That Defined the Alley

Tri-State Tornado, March 18, 1925. A single F5 tornado tracked 219 miles across Missouri, Illinois, and Indiana in about three and a half hours. It killed 695 people, the deadliest single tornado on record in US history. The full outbreak that day claimed 747 lives. The Tri-State remains the standard for both longevity and death toll, and it is the reason every NOAA tornado dataset has a 1925 reference point.

Super Outbreak, April 3 to 4, 1974. 148 confirmed tornadoes across 13 US states and Ontario, Canada in less than 24 hours, including 30 violent F4 or F5 tornadoes, the most violent tornadoes in any single outbreak on record. 319 people died. 5,484 were injured. Damage ran about $600 million in 1974 dollars, roughly $3.92 billion in 2025 dollars.

Greensburg, Kansas EF5, May 4, 2007. The first tornado officially rated EF5 on the Enhanced Fujita Scale, which had taken effect three months earlier. Winds exceeded 205 mph, the path was 1.7 miles wide, 95 percent of Greensburg was destroyed, and 11 people died. The town’s rebuild required every new structure to meet LEED Platinum certification, which by 2026 made Greensburg the most LEED-certified city per capita in the US.

Joplin, Missouri EF5, May 22, 2011. 158 deaths, the deadliest single tornado in the US since 1947. Winds near 200 mph, path 1.3 miles wide, $3.71 billion in damage. Joplin was the costliest single tornado on record at the time. Read the full federal record on the NWS heritage page.

Moore, Oklahoma EF4, May 20, 2013. Hit a metro area already scarred by a 1999 tornado. Winds near 210 mph in a 1.3-mile-wide path, 24 deaths, and roughly $2 billion in damage. Moore is the textbook case for the limits of warning systems even in the most weather-aware part of the country.

2011 Super Outbreak, April 25 to 28. 368 tornadoes in four days, 292 of them on April 27 alone, with four EF5s and eleven EF4s. 324 tornado deaths. $10.2 billion in damage, the costliest tornado outbreak in US history. The 2011 outbreak is the event that announced, in numbers, the eastward shift of severe weather, hitting Mississippi, Alabama, Tennessee, and Georgia hardest.

Tornado Alley Is Moving East

In a 2018 paper in npj Climate and Atmospheric Science, meteorologists Victor Gensini of Northern Illinois University and Harold Brooks of NOAA’s National Severe Storms Laboratory analyzed tornado data from 1979 to 2017 and found a statistically significant eastward shift in both tornado frequency and tornado-favorable atmospheric environments.

Their findings, in short:

Classic Alley is declining. Texas, Oklahoma, and northeast Colorado have shown significant decreasing trends over the 38-year window.

The Mid-South is rising. Mississippi, Alabama, Arkansas, Missouri, Illinois, Indiana, Tennessee, and Kentucky have shown significant increasing trends.

The center has moved. The historical activity center has shifted 400 to 500 miles east, into what is now generally called Dixie Alley.

Mechanism, per the same researchers and follow-on work: a long Southwest drought is supplying drier air that suppresses storm formation in its lee, the dry-line boundary has migrated about 140 miles east since the late 1800s, Gulf of Mexico water temperatures are 1 to 2 degrees Celsius warmer than mid-century averages, and the jet stream sits further south more often than it did. Strong tornadoes, EF3 and up, have more than doubled in Dixie Alley states since 1990 and dropped about 30 percent across the Great Plains. Roughly 40 million Americans now live in counties where violent-tornado activity is rising.

The Enhanced Fujita Scale, Briefly

Tornadoes are rated on the Enhanced Fujita Scale, which replaced the original Fujita Scale on February 1, 2007. The EF Scale assigns a rating after the fact based on observed damage and estimated wind speed.

EF0: 65 to 85 mph. Light damage, branches snapped, shingles peeled.

EF1: 86 to 110 mph. Moderate. Roofs stripped, mobile homes pushed off foundations.

EF2: 111 to 135 mph. Considerable. Roofs torn off, mobile homes demolished.

EF3: 136 to 165 mph. Severe. Most walls of well-built homes collapse.

EF4: 166 to 200 mph. Devastating. Well-built homes leveled.

EF5: Over 200 mph. Incredible. Total destruction, structural damage to reinforced concrete buildings, debris turned into projectiles.

EF4 and EF5 tornadoes account for roughly 0.1 percent of all US tornadoes but cause the majority of tornado deaths. Weak (EF0 to EF1), strong (EF2 to EF3), and violent (EF4 to EF5) are the standard severity buckets.

Cities and Counties at the Highest Risk

Oklahoma City, Oklahoma. Capital of classic Tornado Alley by both reputation and record. The city has been hit repeatedly, most famously in May 1999, May 2003, and the May 2013 Moore strike just south of the metro.

Tulsa, Oklahoma. Eastern Oklahoma is also a recurring violent-tornado target.

Wichita, Kansas. The largest city in the highest-density tornado state.

Kansas City, Missouri. Sits at a crossroads of three severe-weather regimes.

Amarillo and Wichita Falls, Texas. Texas Panhandle and North Texas remain among the busiest corridors in the country.

Safety in Tornado Alley

Mobile and manufactured homes are the most dangerous structures in a tornado. Roughly 72 percent of US tornado fatalities happen in homes, and 54 percent of those happen in mobile homes. Mobile-home residents are 15 to 20 times more likely to die in a tornado than residents of permanent structures. NOAA and FEMA recommend evacuation when a Tornado Watch is issued, not when a Warning is issued. By the time a Warning hits, the storm is too close and roads may be impassable. The shelter target is a sturdy single-family home with a basement, a designated tornado shelter, a reinforced concrete building, or a community shelter. Storm cellars are common in Oklahoma and Kansas for a reason.

For details on the eastern equivalent of these threats, see our piece on Dixie Alley.

Frequently Asked Questions

What states are in Tornado Alley?

Classic Tornado Alley covers northern Texas, Oklahoma, Kansas, and Nebraska. Broader definitions include South Dakota, Iowa, Missouri, Illinois, Indiana, western Ohio, and southern Minnesota. The boundaries are unofficial and informal, not a NOAA designation.

Which state has the most tornadoes?

Texas has the most tornadoes by absolute count, averaging 155 a year per NOAA Storm Prediction Center records. Kansas has the most per square mile at about 4.4 tornadoes per 100 square miles, and Kansas produces about four times more strong (EF3 or higher) tornadoes per square mile than Florida.

When did the term Tornado Alley originate?

Air Force meteorologists Ernest J. Fawbush and Robert C. Miller coined “Tornado Alley” in 1952 as the title of a research project on severe weather across Texas and Oklahoma. The phrase reached the general public in May 1957 when the New York Times used it as a headline.

When is tornado season in Tornado Alley?

Peak tornado season runs April through June, with May the busiest month at an average of 269 US tornadoes. April produces the largest share of violent (EF4+) tornadoes. The threat shifts northward as the season progresses, from the southern Plains in April to the northern Plains and Midwest by June.

Is Tornado Alley shifting east?

Yes. Peer-reviewed research from Victor Gensini at Northern Illinois University and Harold Brooks at NOAA documents a 400 to 500 mile eastward shift in tornado activity from 1979 to 2017. Strong tornadoes have more than doubled across Mississippi, Alabama, and surrounding states since 1990, while dropping about 30 percent across the Great Plains.

What is the deadliest tornado in US history?

The Tri-State Tornado of March 18, 1925 is the deadliest single tornado in US history. It tracked 219 miles across Missouri, Illinois, and Indiana in about three and a half hours and killed 695 people. The full outbreak that day claimed 747 lives.

What is the difference between Tornado Alley and Dixie Alley?

Classic Tornado Alley is the Great Plains corridor: northern Texas, Oklahoma, Kansas, Nebraska. Dixie Alley is the southeastern corridor: Mississippi, Alabama, Tennessee, Arkansas, Louisiana, with extensions into Georgia and Kentucky. Dixie Alley produces fewer tornadoes per year but more deaths per tornado, and it now sees a unique fall peak in November and December that classic Tornado Alley does not.

See the Long-Range Forecast for Tornado Alley

May is the peak month. Farmers’ Almanac long-range forecasts cover the country season by season, town by town. See the outlook for the Plains and Mid-South before the watches start firing.

View the Long-Range Forecast

Quick Reference

• What it is: A secondary tornado-prone region in the southeastern US, distinct from classic Tornado Alley. Term coined by NOAA’s Allen Pearson in 1971.
• States included: Mississippi, Alabama, Arkansas, Louisiana, Tennessee, plus parts of Georgia, Kentucky, South Carolina, and North Carolina.
• Why it is deadlier: Nighttime tornadoes (2.5x more fatal), high mobile-home density (15-20x death risk), tree cover, rain-wrapped storms, and a longer season.
• Most active state: Mississippi, averaging about 115 tornadoes a year, far above the national state average.
• Unique season pattern: Two peaks. Spring (Feb to mid-April) AND a secondary surge in November and December that exists nowhere else in the US.
• Worst recent outbreak: The 2011 Super Outbreak. 368 tornadoes, four EF5s, 348 deaths, $10.2 billion in damage.

Mississippi sees about 115 tornadoes a year, more than any other state per capita, and Tennessee logs the highest share of nighttime tornado fatalities in the country at over 73 percent. Both states sit inside Dixie Alley, the secondary tornado belt that runs across the Deep South. Classic Tornado Alley out on the Plains gets the storm-chaser footage. Dixie Alley gets the funerals. Below is what the term means, why this region runs deadlier per tornado, and how the geography is shifting in a way that puts more people in its path every year.

What is Dixie Alley?

Dixie Alley is the informal name for a secondary tornado-prone region in the southeastern United States. The term was coined in 1971 by Allen Pearson, then director of the National Severe Storms Forecast Center, the predecessor to today’s NOAA Storm Prediction Center. Pearson used it to flag a region that produces fewer total tornadoes than Tornado Alley but consistently higher death tolls.

The core states are Mississippi, Alabama, Arkansas, Louisiana, and Tennessee. The footprint stretches into parts of Georgia, Kentucky, southeastern Missouri, upstate South Carolina, and western North Carolina. The region’s defining feature is access to deep, warm Gulf of Mexico moisture, which fuels the high-precipitation supercells that dominate Dixie Alley severe weather. These storms wrap their tornadoes in heavy rain, a condition meteorologists call rain-wrapped, and that visibility problem is part of why the region is so dangerous.

Why Dixie Alley Is Deadlier Than Classic Tornado Alley

Dixie Alley produces fewer tornadoes per year than the classic Tornado Alley of Oklahoma and Kansas. It produces more tornado deaths. Five overlapping factors explain the disparity.

1. Nighttime tornadoes. Tornadoes that strike after dark are roughly 2.5 times more likely to kill people than daytime tornadoes, because most residents are asleep and weather alerts have to wake them. The Gulf of Mexico keeps the air over Dixie Alley unstable long after sunset, which is why Tennessee, Arkansas, Alabama, and Mississippi all see a majority of their tornado deaths at night. Tennessee is the worst offender at over 73 percent.

2. Mobile home density. A tornado that hits a manufactured home produces 15 to 20 times the death risk of one that hits a stick-built house. Dixie Alley has the highest concentration of manufactured housing in the country. Mississippi sits at about 15 percent, South Carolina at 14.2, and Louisiana at 12.6, all above the US average. Mobile homes account for only about 8 to 12 percent of housing stock in the region but generate 53 percent of tornado deaths in homes.

3. Tree cover and rain-wrapped storms. Pine forest, hardwoods, and rolling terrain block sightlines. By the time a Mississippi family hears the train-roar, the tornado is already on the lawn. Heavy rain wrapped around the funnel makes visual confirmation impossible. Plains tornadoes, by contrast, are visible across the wheat for miles.

4. A longer and offset season. Tornado Alley peaks once, in May and June. Dixie Alley peaks twice, in February to mid-April and again in November and December. That late-fall second peak is unique in the country and is driven by faster jet-stream winds that produce faster-moving tornadoes. Faster ground speed means less reaction time.

5. Higher population density and weaker shelter infrastructure. The Plains have storm cellars baked into local building tradition. The Southeast does not. Add denser populations and you get more people in the path with fewer hardened places to go.

Notable Dixie Alley Tornado Outbreaks

2011 Super Outbreak (April 25 to 28, 2011). The largest tornado outbreak in US history. Over four days, 368 confirmed tornadoes touched down. April 27 alone produced 224 of them, the most active tornado day ever recorded. The outbreak generated four EF5s and eleven EF4s. The four EF5 tornadoes hit Philadelphia and Kemper County in Mississippi, Hackleburg-Phil Campbell-Tanner-Harvest in Alabama, Smithville Mississippi into Shottsville Alabama, and Fyffe-Rainsville-Sylvania Alabama into Rising Fawn Georgia. Total death toll: 348, with Alabama alone losing 238 lives. Damage ran $10.2 billion in 2011 dollars per NOAA NCEI.

March 3, 2019 outbreak. A six-hour severe-weather event spawned 42 tornadoes across Alabama, Georgia, Florida, and South Carolina. The deadliest was an EF4 that ran 68.6 miles from Beauregard through Smiths Station, Alabama, into Talbotton, Georgia, with peak winds of 170 mph and a 76-minute lifespan. It killed 23 people in Lee County, Alabama, the worst tornado in the county since 1875 and the deadliest US tornado since the 2013 Moore, Oklahoma storm.

March 31 to April 1, 2023 outbreak. A multi-day outbreak produced more than 145 tornadoes across the southern and central US, with the heaviest damage concentrated across Dixie Alley. NOAA pegged total damage at about $5.7 billion, a reminder that the region’s worst outbreaks are not historical artifacts but a current and ongoing threat.

State-by-State Tornado Frequency

Mississippi. Roughly 115 tornadoes a year on a five-year running average, the highest in Dixie Alley and far above the national state-average of about 24. Mississippi has logged the most tornadoes of any state across the past five years.

Alabama. About 90 tornadoes a year on the 2018 to 2022 baseline. The state took the brunt of the 2011 Super Outbreak and continues to log catastrophic events at a regular cadence.

Tennessee. Lower raw count than Mississippi or Alabama, but the deadliest fatality profile in the country, with more than 73 percent of tornado deaths happening at night per NWS data.

Louisiana, Arkansas, Georgia. Each averages 30 to 50 tornadoes a year, with Louisiana additionally exposed to Gulf hurricane spawn. In 2022, Mississippi, Alabama, and Texas combined for 31 percent of all US tornadoes. For more on how those tornado losses fit a wider state-by-state weather risk picture, see our piece on the worst weather states in the US.

Tornado Alley Is Migrating Into Dixie Alley

Peer-reviewed research from Victor Gensini at Northern Illinois University has documented a 400 to 500 mile eastward migration of tornado activity over the past forty years. Tornadoes that used to concentrate in northeastern Texas and south-central Oklahoma now show up more often in eastern Missouri, Arkansas, western Tennessee and Kentucky, and northern Mississippi and Alabama. In other words, classic Tornado Alley is moving into Dixie Alley.

The drivers are physical and well-documented. The American Southwest has been in a long-running drought, which produces a high-pressure dome that suppresses storm formation in its lee. The dry line, the boundary between dry desert air and humid Gulf air, has shifted about 140 miles east since the late 1800s. Gulf of Mexico water temperatures are 1 to 2 degrees Celsius warmer than mid-century averages, providing more moisture to the convective engine. The jet stream sits further south more often than it did, parking moisture over the Mississippi Delta in seasons it once skipped. The implication is that Dixie Alley’s hazard burden is rising in a region that is less prepared, on average, to absorb it.

The climate-driver context is part of a larger pattern. For background on the seasonal patterns that influence severe weather across the country, see our explainers on El Nino and La Nina.

Shelter and Safety in Dixie Alley

Dixie Alley’s lethality profile means safety advice that works in Tornado Alley is not enough here. Three rules carry the most weight.

If you live in a manufactured home, leave it for any tornado warning. Per FEMA P-320 standards, a properly engineered above-ground safe room can withstand 250 mph winds, but it must be anchored to a reinforced concrete slab at least 4 inches thick with rebar or post-tension cable. If your home does not have that, your shelter plan is to leave for a community shelter or a reinforced public building before the storm arrives, not when it is on top of you.

Get a NOAA Weather Radio with battery backup. Dixie Alley tornadoes hit at night. Phone alerts can fail. A weather radio that wakes you out of a sound sleep is the difference between sheltering and sleeping through it.

Have a written shelter plan with multiple exit routes. Trees come down across rural roads in the South in seconds. A single planned route is one tree away from being closed. Practice the drill before the season starts, in late January for the spring peak and again in late October for the fall peak.

Frequently Asked Questions

What states are in Dixie Alley?

The core Dixie Alley states are Mississippi, Alabama, Arkansas, Louisiana, and Tennessee. The footprint extends into parts of Georgia, Kentucky, southeastern Missouri, upstate South Carolina, and western North Carolina.

Why is Dixie Alley more dangerous than Tornado Alley?

Dixie Alley produces fewer total tornadoes than Tornado Alley but more tornado deaths because of nighttime occurrence, high mobile-home density, tree cover that hides approaching storms, rain-wrapped tornadoes, a longer season, and weaker shelter infrastructure across the region.

When is Dixie Alley tornado season?

Dixie Alley has a bimodal tornado season. The primary peak runs from February through mid-April. A secondary peak runs in November and December that does not occur anywhere else in the US, driven by faster cool-season jet-stream winds and persistent Gulf moisture.

Which Dixie Alley state has the most tornadoes?

Mississippi averages roughly 115 tornadoes a year, the highest in Dixie Alley and well above the national state average of about 24. Alabama follows at about 90 a year.

Is Tornado Alley shifting into Dixie Alley?

Yes. Peer-reviewed research from Northern Illinois University documents a 400 to 500 mile eastward shift in tornado activity over the past forty years. Drivers include long-term Southwest drought, a 140-mile eastward shift in the dry line since the late 1800s, warmer Gulf of Mexico water, and a more southerly jet-stream position.

Who coined the term Dixie Alley?

Allen Pearson, then director of NOAA’s National Severe Storms Forecast Center, coined the term in 1971 to describe a southeastern region with fewer tornadoes than the Plains but a higher death rate per tornado.

See the Long-Range Forecast for Your Area

Severe-weather seasons hit Dixie Alley twice a year. Farmers’ Almanac long-range forecasts cover the country season by season, town by town, so you can see what is coming before the watches are issued.

View the Long-Range Forecast

Quick Reference

• #1 worst weather state: Texas. 155 tornadoes a year, 190 billion-dollar disasters since 1980, every major hazard type.
• Most billion-dollar disasters: Georgia at 134, the highest frequency of any state per NOAA NCEI.
• Most hurricane landfalls: Florida, with more than 120 documented since 1851.
• Most flood disasters: Louisiana, with 10 billion-dollar flood events, the highest of any state.
• Hail capital: Colorado. 94 hail events per year and 38 billion-dollar hailstorms since 1980.
• Ranked by: tornado frequency, NOAA billion-dollar disaster count, hurricane landfalls, severe storm and hail incidence, and temperature extremes.

Texas logs about 155 tornadoes a year, has racked up 190 billion-dollar weather disasters since 1980, and is the only state in the country that has to plan for tornadoes, hurricanes, hailstorms, derechos, wildfires, droughts, and flash flooding in the same calendar. That is how a place most travelers picture as wide open and sunny ends up at the top of the worst weather states list. The ranking below uses long-run NOAA data, not a single bad season, and it tracks the chronic weather burden a resident actually lives with year after year.

How We Picked the Worst Weather States

Worst is a slippery word, so the ranking has to be tied to numbers. The list below weighs five factors equally, all drawn from federal data: tornado frequency from the NOAA Storm Prediction Center, the count of billion-dollar weather and climate disasters from NOAA NCEI covering 1980 to 2024, hurricane and tropical cyclone landfalls from the National Hurricane Center, severe thunderstorm and hail incidence from National Weather Service warning records, and temperature extremes from the NOAA Climate Extremes Index.

A few notes before you read on. Severity here is composite, not single-event. A state earns a spot for facing many hazard types across the year, not for one historic storm. The list is also US-only, fifty states. Territories are not ranked. And the rankings are about exposure and frequency, not whether residents like the weather. If you love four seasons of severe storms, Oklahoma will look like home; if you do not, you will have read enough by item three.

The 10 Worst Weather States in the US

1. Texas. Texas tops the list because it pulls every lever at once. The state averages 155 tornadoes a year, the highest absolute count in the country. Since 1980 it has logged 190 billion-dollar weather and climate disasters, including 126 severe storms, hurricanes from Carla to Harvey, drought after drought, and historic hail. Hurricane Harvey in 2017 alone delivered roughly 60 inches of rain to the Houston area and caused about $160 billion in damage. Between 2018 and 2022, the National Weather Service issued 137,523 watches, warnings, and advisories for Texas. The trade-off Texans hear all the time is “everything is bigger here.” Weather included.

2. Florida. Florida holds the national record for hurricane landfalls, with more than 120 documented since 1851. Since 1980, the state has racked up roughly 80 billion-dollar weather disasters, 36 of them hurricanes or tropical cyclones. Hurricane Ian in 2022 came ashore as a Category 4 with 150 mph winds, drove a 10 to 15 foot storm surge into southwest Florida, destroyed or damaged more than 30,000 homes, and ran a damage bill of about $112 billion. The peninsula is the only state exposed to both Atlantic and Gulf storm tracks, which is why hurricane season here lasts five months in fact and twelve months in mind.

3. Louisiana. Louisiana has logged 10 billion-dollar flood events since 1980, the highest count of any state, on top of repeated Category 3 and 4 hurricane landfalls. Hurricane Katrina in 2005 caused about $201.3 billion in damage in 2024 dollars, the costliest US hurricane on record, and is responsible for 1,833 deaths. Hurricane Ida in 2021 came ashore as a Category 4 sixteen years to the day after Katrina. Most of metro New Orleans sits below sea level, which is why a Louisiana resident learns levee terminology the way other Americans learn weekend forecasts.

4. Kansas. Kansas sits near the heart of Tornado Alley and ranks second nationally with about 96 tornadoes a year. Between 1950 and 2016, the state recorded 49 violent tornadoes rated EF4 or stronger. About 60 to 70 percent of Kansas tornado activity hits between April and June. The state has logged 128 billion-dollar disasters since 1980, third-highest in the country, and counts large hail and damaging derecho winds among its yearly hazards. The 2007 EF5 tornado that struck Greensburg destroyed roughly 95 percent of the town. A Kansas spring sky can turn green in the time it takes to bring in the laundry.

5. Oklahoma. Oklahoma averages 68 tornadoes a year and has produced 65 EF4-or-stronger tornadoes since 1950, one of the highest violent-tornado counts in the country. The May 2013 Moore tornado was a long-lived multivortex storm that took 23 lives and demolished an elementary school. The state has logged 120 billion-dollar disasters since 1980 and faces large hail, derecho winds, and severe heat with regularity. Oklahoma also sees more felt earthquakes now than it did in 2000, owing to wastewater injection from oil and gas operations. The local joke that you can experience all four seasons in a single spring afternoon is a joke because it is true.

6. Colorado. Colorado is the hail capital of the United States. The state averages about 94 hail events a year and roughly $151 million in annual hail damage, and has seen 38 billion-dollar hailstorms since 1980. The 2023 hail season set a state record, with 34 reports of hail at least three inches across, a threefold increase from 2019. The mountain-plains geography also produces blizzards in April and May, summer flash floods, and explosive wildfire weather. The Marshall Fire in Boulder County in December 2021 destroyed more than 1,000 structures and ran $513 million in damage. Coloradans plan for snow and shop for hail nets in the same week.

7. Missouri. Missouri sits at the meeting place of Gulf moisture, plains tornadoes, and major river flooding. The state has recorded 2,555 tornadoes since 1950, with May as the peak month. St. Louis alone accounts for 68 of those tornado events, the highest concentration in the state. Missouri has logged 120 billion-dollar disasters since 1980, faces flooding from both the Mississippi and Missouri Rivers, and sees regular winter ice storms. A 2020 derecho carved across the southern half of the state with 60-plus mph winds, large hail, and three to five inches of rain in a few hours.

8. Georgia. Georgia leads the country in raw billion-dollar disaster frequency, with 134 events since 1980 per NOAA NCEI. Cumulative damage exceeds $150 billion. The state catches Atlantic hurricane landfalls, tropical cyclone remnants that stall and dump rain, spring tornado outbreaks, summer thunderstorms, ice storms in the foothills, and severe heat in the south. Hurricane Helene in 2024 spawned tornadoes across the state and produced significant inland flooding. The breadth of hazards is what puts Georgia near the top, even when no single storm dominates the headline.

9. Illinois. Illinois sits in the Midwest severe-weather corridor and has logged 128 billion-dollar disasters since 1980. The August 2020 Midwest derecho crossed the state with 80-plus mph winds, hail, and tornadoes, and remains one of the costliest thunderstorm complexes in US history. Tornado activity averages 15 to 25 a year, Mississippi River flooding is a recurring threat, and the Chicago area pulls in lake-effect snow and brutal winter wind off Lake Michigan. Add ice storms in central Illinois and the state runs the full severe-weather menu.

10. North Carolina. North Carolina has logged 121 billion-dollar disasters since 1980 and faces a rising threat from tropical systems that stall and unload rain on the Appalachian foothills. Hurricane Florence in 2018 dropped more than 20 inches of rain on parts of the state and ran a damage bill above $24 billion. Hurricane Helene in 2024 dumped over 30 inches of rain in some western North Carolina mountain locations and produced catastrophic flooding far from the coast. Spring tornadoes, ice storms in the Piedmont, and elevation-driven snowfall round out the hazard list.

Tornadoes, Hurricanes, and Hail: Where the Numbers Cluster

Three hazard categories explain most of this list. Tornadoes concentrate in a corridor that runs from northern Texas through Oklahoma, Kansas, Missouri, and Illinois. Hurricane landfalls cluster on the Gulf and South Atlantic coasts, which is why Florida, Louisiana, Texas, Georgia, and North Carolina all appear. Hail damage centers on the high plains, with Colorado and Texas absorbing the worst of it. A state usually earns a top-10 slot by sitting at the intersection of two of those clusters, not just one.

For more on the seasonal climate drivers behind these patterns, see our explainers on what El Nino is and what La Nina is. For the storm types that drive much of the damage, our hurricane names reference and historic blizzards archive cover the named events.

Worst Weather States vs. Worst Weather Cities

State rankings and city rankings tell different stories. Cities live or die by their own microclimate, which is why a state with mostly mild weather can still have a single brutal city, and a state on the worst list can have a few pleasant ones. Our companion piece on the 10 worst weather cities uses sunshine, precipitation, humidity, and temperature as the lens. The state list above uses disaster frequency and chronic hazard exposure. Use both. A retiree picking a town wants the city number; an emergency manager picking a state wants the disaster number.

If you want a finer cut on chronic conditions, see America’s stormiest cities, which ranks by lightning and severe-storm days, and top 10 cloudiest US states, which is a different cut on bad weather entirely.

Sources and Methodology Notes

All disaster counts are drawn from the NOAA NCEI Billion-Dollar Weather and Climate Disasters database, which tracks events whose damage exceeds $1 billion in CPI-adjusted dollars. Tornado counts are state averages from the NOAA Storm Prediction Center WCM tornado statistics. Hurricane data comes from the National Hurricane Center and FEMA disaster declarations. Severe storm and hail data comes from the Insurance Information Institute compilations of NWS warning records.

Disaster counts run through 2024; partial-year totals were excluded. Tornado averages cover the full instrumental record from 1950, with the post-1990 period weighted more heavily because Doppler radar improved tornado detection. The ranking is descriptive, not predictive. A quiet year does not move a state down the list, and a single bad year does not move one up.

Frequently Asked Questions

What is the worst weather state in the US?

Texas is the worst weather state in the US by composite NOAA data. It logs the most tornadoes, has 190 billion-dollar weather disasters since 1980, and is the only state exposed to all major hazard categories: tornadoes, hurricanes, hail, derechos, drought, wildfire, and flash flooding.

Which state has the most tornadoes?

Texas has the most tornadoes in absolute terms, averaging 155 a year per NOAA Storm Prediction Center records. Per square mile, Kansas and Oklahoma rank higher, with Kansas averaging 96 a year and Oklahoma 68 a year despite being much smaller than Texas.

Which state gets hit by the most hurricanes?

Florida has the most hurricane landfalls of any US state, with more than 120 documented since 1851. The peninsula is exposed to both Atlantic and Gulf of Mexico storm tracks, which no other state shares.

Which state has the most billion-dollar weather disasters?

Texas has the most billion-dollar weather and climate disasters at 190 since 1980, per NOAA NCEI. Georgia leads on raw frequency at 134 events, and Kansas and Illinois tie for third at 128 events each.

What is the safest US state for weather?

States in the Mountain West and Pacific Northwest typically have the lowest disaster frequency. Oregon, Washington, Idaho, Utah, and Nevada show up consistently as the lowest-risk states for tornadoes, hurricanes, and hail combined, though they carry their own threats from wildfire and winter storms.

How does Tornado Alley compare to Dixie Alley?

Tornado Alley, centered on Oklahoma, Kansas, and northern Texas, peaks in spring with classic supercells. Dixie Alley, covering Mississippi, Alabama, Tennessee, and parts of Arkansas and Georgia, sees more nighttime tornadoes and a longer season that runs into late fall, which is part of why Dixie Alley tornadoes are deadlier per event.

See the Long-Range Forecast for Your State

Worst-weather rankings are about the past. Farmers’ Almanac long-range forecasts cover what is coming next, season by season, town by town. Plan around the storm window before it opens.

View the Long-Range Forecast

Quick Reference

• Top picks: Lavender, salvia, yarrow, sedum, agastache, echinacea, russian sage, black-eyed susan, coreopsis, gaura.
• Best shrubs: Juniper, butterfly bush, ninebark, rugosa rose, smoke bush.
• Best grasses: Blue fescue, little bluestem, switchgrass, Mexican feather grass.
• Best planting time: Fall. Roots establish through winter and the plant arrives spring already drought-ready.
• Water savings: 50 to 70 percent less than a traditional perennial bed once established (year three on).
• Common mistake: Overwatering. Drought tolerant plants want infrequent, deep soaking, not daily sprinkles.

A garden that lives on rainfall is no longer a Southwestern thing. Water restrictions, hotter summers, and busier lives have moved drought tolerant plants from a niche to a mainstream choice across most of the country. Below is what drought tolerant actually means, twenty plants that earn the label, regional picks for the Southwest through the Southeast, and the planting timing that decides whether they live through their first dry summer.

What “Drought Tolerant” Actually Means

Three terms get used interchangeably and should not be. Drought tolerant means the plant can survive an extended dry period after it is established (typically year three onward) without irrigation. Drought resistant is sometimes used as a synonym but technically means the plant resists water loss through structural features (waxy leaves, deep taproots, succulent tissue). Xeriscape is the landscape design philosophy that uses drought tolerant plants plus mulch, smart irrigation, and grouped water needs to minimize total garden water use.

Establishment matters. Even the most drought tolerant plant needs regular water for the first one to two years to grow the root system that lets it skip rain later. Plant a yarrow in May, neglect it in July, and it dies. Plant the same yarrow in October, water it through fall, and by July it survives on its own.

20 Drought Tolerant Plants Worth Planting

All recommended in published lists from EPA WaterSense and university extension drought-plant guides.

Perennials

1. Lavender (Lavandula). Zones 5 to 9. Full sun. 1 to 3 feet. Purple bloom, silver foliage, deer resistant, pollinator magnet. Wants well-drained soil and hates wet feet.

2. Salvia. Zones 4 to 9. Full sun. 1 to 3 feet. Purple, blue, red, or white spikes through summer. Hummingbird favorite.

3. Yarrow (Achillea). Zones 3 to 9. Full sun. 1 to 3 feet. Yellow, white, pink, red flat-top blooms. Tolerates poor soil. Spreads.

4. Sedum (Stonecrop). Zones 3 to 9. Full sun. Ground cover to 2 feet. Succulent leaves, late summer blooms. Bulletproof.

5. Agastache (Hyssop). Zones 5 to 10. Full sun. 2 to 4 feet. Long spikes of purple, orange, or pink, hummingbird favorite, fragrant foliage.

6. Echinacea (Coneflower). Zones 3 to 9. Full sun to part shade. 2 to 4 feet. Native, butterfly favorite, cold tolerant.

7. Russian sage (Perovskia). Zones 4 to 9. Full sun. 3 to 5 feet. Long lavender-blue plumes from midsummer to fall, deer resistant, tough.

8. Black-eyed susan (Rudbeckia). Zones 3 to 9. Full sun. 2 to 3 feet. Native gold daisies July to October. Reseeds.

9. Coreopsis (Tickseed). Zones 3 to 9. Full sun. 1 to 3 feet. Yellow daisies all summer. Cuts well for vases.

10. Gaura (Whirling Butterflies). Zones 5 to 9. Full sun. 2 to 3 feet. Airy white or pink wands. Long bloom window.

Shrubs

11. Juniper. Zones 3 to 9. Full sun. From ground covers to 30-foot trees. Evergreen, almost no maintenance once rooted.

12. Butterfly bush (Buddleia). Zones 5 to 9. Full sun. 4 to 10 feet. Long lilac, white, or magenta flower spikes. Check local invasive status before planting.

13. Ninebark (Physocarpus). Zones 2 to 8. Full sun to part shade. 4 to 8 feet. Native, gold or purple foliage cultivars, cold tolerant.

14. Rugosa rose. Zones 2 to 7. Full sun. 4 to 6 feet. Salt and drought tolerant. Big rose hips after bloom.

Grasses

15. Blue fescue (Festuca glauca). Zones 4 to 8. Full sun. 6 to 12 inches. Tight blue tufts. Border classic.

16. Little bluestem (Schizachyrium). Zones 3 to 9. Full sun. 2 to 4 feet. Native prairie grass with russet fall color.

17. Switchgrass (Panicum). Zones 3 to 9. Full sun to part shade. 3 to 6 feet. Native, vertical, golden seed heads.

18. Mexican feather grass (Nassella). Zones 6 to 10. Full sun. 2 feet. Soft, hair-thin foliage that catches the wind.

Succulents and natives

19. Agave. Zones 7 to 11. Full sun. Architectural rosette. Best for Southwest and Mediterranean climates.

20. Penstemon (Beardtongue). Zones 3 to 10. Full sun. 1 to 3 feet. Native, tubular flowers, hummingbird favorite.

Drought Tolerant Plants by Region

Southwest (Arizona, New Mexico, Nevada, west Texas). Agave, ocotillo, penstemon, desert marigold, Mexican feather grass, yucca, agastache, salvia greggii, lavender. Plant fall through early spring. Use decomposed-granite mulch.

Mountain West (Colorado, Utah, Wyoming, Idaho). Russian sage, yarrow, blue mist spirea, blanket flower (gaillardia), little bluestem, juniper, native penstemon, lambs ear, agastache. Plant in early fall once temperatures cool but the ground is still workable.

Great Plains and Midwest. Echinacea, black-eyed susan, switchgrass, little bluestem, butterfly weed, prairie smoke, native milkweed. Match natives to local soils for the lowest care load.

Southeast. Lantana, salvia, gaura, coreopsis, beautyberry, native rosemary (Conradina), yucca, ninebark, gaillardia. The Southeast can be unexpectedly dry late summer; drought tolerance pays off in August.

California and Mediterranean climates. Lavender, rosemary, ceanothus, salvia clevelandii, Mexican sage, California poppy, yarrow, agave, manzanita. Many California natives go fully summer-dormant and bloom on winter rain.

Care Essentials

Plant in fall. Roots grow through winter while the top stays dormant. By the time spring heat arrives, the plant is already anchored. Spring planting works but burns more water and risks first-summer mortality.

Water deep, water rare. The training rule for the first two years: deep soak (long, slow watering that wets the root zone fully) once a week instead of daily sprinkles. Deep watering forces roots downward. Frequent shallow watering keeps roots near the surface where they cook.

Mulch heavy. Two to four inches of organic mulch (bark, wood chips, pine straw) cuts evaporation 25 to 50 percent and keeps roots cool. Use gravel or decomposed granite for desert plantings that hate organic mulch.

Improve drainage, not fertility. Most drought plants prefer lean, fast-draining soil. Skip the rich amendments. Heavy compost can rot the roots of a sage or a lavender.

Year-three water schedule. Once established, most drought plants need 0 to 0.5 inches of supplemental water per week in summer, depending on rainfall. Many need none in average years.

Common Mistakes to Avoid

1. Overwatering. Most drought-plant failures are wet feet, not thirst. Stop watering once the plant is established.

2. Calling things drought tolerant that are not. Hydrangea, hosta, astilbe, most ferns, ornamental cabbage, and impatiens want consistent moisture. They do not belong in this category.

3. Planting in spring and skipping the establishment year. A drought tolerant plant is not drought tolerant in year one. Spring planting requires summer babysitting.

4. Skipping mulch. Bare soil between plants doubles evaporation and triples weeding.

5. Mixing thirsty and dry plants in the same bed. The thirsty ones force more watering than the drought plants want. Group by water need (the core xeriscape principle).

Best Days for Planting

By Farmers’ Almanac tradition, plant aboveground perennials and shrubs on a waxing moon (new moon through first quarter) and root-heavy or bulb plants on a waning moon (full through last quarter). The waxing window encourages top growth, which helps a transplant settle. For specific dates, see our Best Days Calendar. For climate context that drives drought cycles, see El Nino and La Nina.

Frequently Asked Questions

What are the best drought tolerant plants?

Lavender, salvia, yarrow, sedum, agastache, echinacea, russian sage, black-eyed susan, coreopsis, and gaura are the most reliable drought tolerant perennials across most US climate zones. For shrubs, juniper and ninebark. For grasses, little bluestem and switchgrass.

When is the best time to plant drought tolerant plants?

Fall, six to eight weeks before the first hard frost. Roots grow through winter while the top is dormant, so the plant is established by the time summer heat arrives. Spring planting works but requires more babysitting through the first summer.

How often should I water drought tolerant plants?

Year one: deep soak once a week. Year two: deep soak every two to three weeks in summer. Year three onward: most drought tolerant plants need little to no supplemental water in average rainfall years.

What is the difference between drought tolerant and xeriscape?

Drought tolerant describes a plant. Xeriscape describes a whole landscape design that combines drought tolerant plants with mulch, drainage, smart irrigation, and grouped water needs. A drought tolerant plant can fit any garden style. A xeriscape is the full system.

Are hydrangeas drought tolerant?

No. Hydrangeas need consistently moist soil and wilt quickly under heat or drought. They are often misclassified, but they belong in the regular-watering category, not the drought tolerant one.

How much water does a drought tolerant garden save?

A mature drought tolerant garden uses 50 to 70 percent less water than a traditional perennial bed once plants are established (year three onward). EPA WaterSense estimates show municipal water savings of 33 to 60 percent for landscapes converted to native and drought tolerant plants.

Plant at the Right Time, Every Time

The Farmers’ Almanac Planting Calendar uses your zip code, your hardiness zone, and the Moon’s phase to give you the best window for every crop. Plant smarter, harvest more.

Open the Planting Calendar

Quick Reference

• What it is: The crescent moon is the lunar phase when less than 50 percent of the Moon’s illuminated face is visible from Earth.
• Two kinds: Waxing crescent (growing, lit on the right in the Northern Hemisphere, looks like a D) and waning crescent (shrinking, lit on the left, looks like a C).
• How long each lasts: About 7.4 days. Combined, you see crescent phases roughly half of every 29.5-day lunar cycle.
• When to look: Waxing crescent in the western sky just after sunset. Waning crescent in the eastern sky just before sunrise.
• Almanac planting rule: Plant aboveground crops during the waxing moon (new through first quarter). Plant root crops during the waning moon (full through last quarter).
• Earthshine: The faint glow on the Moon’s dark side during a thin crescent. Sunlight reflected off Earth, first explained by Leonardo da Vinci.

A crescent moon is the lunar phase when less than half of the Moon’s lit face is visible from Earth, and it shows up twice in every 29.5-day cycle. The waxing crescent comes right after the new moon, growing a little fatter every night. The waning crescent comes right before the next new moon, fading thinner every night until it disappears. Below is what each one means, why we see it, when to step outside to catch it, and how the Almanac has used it to time planting for two centuries.

What a Crescent Moon Actually Is

The Moon does not make its own light. Half of the Moon is always lit by the Sun, the same way half of any ball in a bright room is always lit. What changes is our viewing angle. As the Moon orbits Earth, the geometry between Sun, Earth, and Moon shifts a little every day, which changes how much of the lit half we can see.

When the Moon is nearly between Earth and the Sun, the lit hemisphere faces away from us and we see almost nothing. That is the new moon. As the Moon moves along its orbit, a thin sliver of the lit hemisphere starts to come into view. That sliver is the crescent. The horns of a crescent always point away from the Sun, and the lit edge always faces toward it. If you can find the Sun, you can always tell which way the Moon is going next.

Waxing Crescent vs Waning Crescent

Waxing crescent. Comes right after the new moon. The lit portion grows from 0 percent to 50 percent over about 7.4 days. In the Northern Hemisphere, the right side of the disk is lit, which produces a shape that resembles the letter D. “Waxing” is an old verb meaning to grow.

Waning crescent. Comes in the last days before the next new moon. The lit portion shrinks from 50 percent back down to 0 percent over about 7.4 days. In the Northern Hemisphere, the left side of the disk is lit, which produces a shape that resembles the letter C. “Waning” is an old word meaning to diminish.

One catch for travelers. South of the equator, the crescents flip. Waxing looks like a backward D and waning like a backward C, because the observer’s view is inverted. So if you visit Australia or Argentina and the Moon looks “wrong,” it is just doing what the Northern Hemisphere does, only mirrored.

Where the Crescent Sits in the 8-Phase Cycle

The full lunar cycle, called the synodic month, runs 29 days, 12 hours, 44 minutes, and 2 seconds. The eight named phases in order:

1. New moon. Moon between Earth and Sun. Invisible.

2. Waxing crescent. 0 to 50 percent lit, growing. About 7.4 days.

3. First quarter. Right half lit (Northern Hemisphere). Often called a half moon.

4. Waxing gibbous. 50 to 100 percent lit, growing.

5. Full moon. Earth between Sun and Moon. Whole face lit.

6. Waning gibbous. 100 to 50 percent lit, shrinking.

7. Last quarter. Left half lit. Also a half moon.

8. Waning crescent. 50 to 0 percent lit, shrinking. About 7.4 days.

Combined, the two crescent phases account for roughly half of every cycle, which is why a crescent moon shows up so often in night-sky photos. For full dates each month, see the moon phases calendar. Curious about the TikTok pairing test? See our piece on moon phase compatibility. Curious about the TikTok pairing test? See our piece on moon phase compatibility.

When and Where to Spot a Crescent Moon

Waxing crescent. Look west, just after sunset, two to three days after the new moon. The young crescent rides low on the western horizon and sets shortly after the Sun, so you have a narrow viewing window. Get to a place with a clear horizon and minimum light pollution. The first sliver of the new lunar cycle is one of the prettiest sights in the sky, and the hardest to catch.

Waning crescent. Look east, about an hour before sunrise, two to three days before the next new moon. This is the morning crescent, lit from the bottom and the left, often hanging in the predawn pink with Venus or Mercury beside it. Worth setting an alarm.

Both crescents sit roughly 10 to 20 degrees above the horizon at their best viewing time. Binoculars are not required, but they reveal earthshine and the texture along the lit edge. Allow your eyes 15 to 20 minutes to adapt to twilight before you judge how clear the view is.

Earthshine: The Old Moon in the New Moon’s Arms

Stare at a thin crescent and you will sometimes see the dark portion of the disk glowing faintly. That ghost light is earthshine. Sunlight bounces off Earth’s clouds, oceans, and ice, hits the unlit side of the Moon, and reflects back to us. From the Moon’s surface, Earth looks roughly 50 times brighter than a full moon looks from Earth, which is why earthshine is bright enough to see at all.

Leonardo da Vinci worked out the explanation around 1510. He realized the Earth itself reflects sunlight, so the dark side of the Moon is not really dark, just faintly lit by Earthshine. Earlier sky-watchers had a more poetic name for it: “the old moon in the new moon’s arms.” Both names still get used. For why we never see the side of the Moon that produces these crescents from the back, see our piece on the far side of the moon. For why we never see the side of the Moon that produces these crescents from the back, see our piece on the far side of the moon.

Earthshine is most visible during a thin waxing crescent (a few days after new moon) or a thin waning crescent (a few days before the next new moon), and it is brightest when there is more cloud and ice on the day side of Earth.

How to Photograph a Crescent Moon

The bright lit edge of a crescent is much brighter than the rest of the scene, which is what makes phone-camera shots so often disappoint. A few practical settings carry most of the work.

For the lit edge alone. Use NASA’s “Looney 11” rule. Set aperture to f/11, shutter speed to 1 over the ISO (so ISO 100 = 1/100 second, ISO 200 = 1/200 second). Manual focus to infinity. Spot meter on the Moon.

For a thin crescent with earthshine. Open the aperture to f/5.6 to f/8, push ISO to 400 to 800, and slow the shutter to 1/30 to 1/8 second. A tripod is essential. The lit edge will overexpose slightly, but the dark side will hold detail.

For composition. Catch the Moon during civil twilight, when the sky still has color, so the foreground does not silhouette into pure black. A 200 mm or longer lens is ideal for filling the frame. White balance daylight (5500 K) keeps the lunar color natural.

The Crescent Moon and Almanac Planting Tradition

Farmers’ Almanac has used the moon as a planting calendar since 1818. The basic rule, drawn from older European and North American farming traditions, is straightforward.

Waxing moon, including the waxing crescent through first quarter, is the time to plant aboveground crops. Tomatoes, beans, peppers, lettuces, corn, melons, squash. The increasing moonlight is traditionally said to encourage leaf and stem growth.

Waning moon, including the waning crescent, is the time to plant root crops. Carrots, beets, onions, garlic, potatoes, turnips. The decreasing moonlight is traditionally said to encourage root development.

Direct scientific evidence for moon-phase planting is limited. The tradition has held up for two centuries because it produces a planting calendar that gardeners actually follow. We give the dates and the framework. Try it for a season against a control row planted off-phase. Decide for yourself. For the current month’s lunar planting windows, see our gardening by the moon calendar.

Cultural and Calendar Use

The crescent moon has marked time for as long as people have looked up. The Islamic calendar is purely lunar, and the start of each month is set by the first sighting of a young crescent after a new moon. The start of Ramadan and the date of Eid both depend on local crescent observation, which is why dates can shift by a day or two between countries. Symbol use spans flags, mosque architecture, and historical Ottoman heraldry.

For pre-electric navigators, the crescent’s horns served as a rough compass. In the Northern Hemisphere, a line drawn from the bottom horn through the top horn and extended down to the horizon points roughly south. Sailors and travelers used the trick for centuries before celestial navigation tools became standard.

Frequently Asked Questions

What is a crescent moon?

A crescent moon is the lunar phase when less than 50 percent of the Moon’s illuminated face is visible from Earth. It happens twice in every 29.5-day cycle: once as a waxing crescent (growing, just after the new moon) and once as a waning crescent (shrinking, just before the next new moon).

What is the difference between waxing and waning crescent?

Waxing crescent grows from 0 to 50 percent illumination over about 7.4 days right after the new moon, and is lit on the right side in the Northern Hemisphere (looks like a D). Waning crescent shrinks from 50 to 0 percent illumination over about 7.4 days right before the next new moon, and is lit on the left side (looks like a C).

When is the best time to see a crescent moon?

Look west just after sunset for the waxing crescent, two to three days after the new moon. Look east about one hour before sunrise for the waning crescent, two to three days before the next new moon. Both sit low on the horizon, so a clear view in that direction matters most.

Why does the crescent moon glow on its dark side?

That faint glow is called earthshine. Sunlight bounces off Earth’s clouds, oceans, and ice and reflects back to dimly illuminate the unlit portion of the Moon. Leonardo da Vinci first explained the effect around 1510. The traditional name for it is “the old moon in the new moon’s arms.”

Is a crescent moon good for planting?

By Farmers’ Almanac tradition, the waxing crescent is ideal for planting aboveground crops like tomatoes, beans, lettuce, and corn. The waning crescent is the time to plant root crops like carrots, beets, onions, and potatoes. Direct scientific evidence for moon-phase planting is limited, but the tradition produces a usable calendar that gardeners have followed for two centuries.

How long does the crescent moon phase last?

Each crescent phase lasts approximately 7.4 days, one quarter of the 29.5-day lunar cycle. Combined, you can see a crescent moon roughly 14.8 days out of every lunar month, or about half the time.

Plan Your Day By the Moon

The Farmers’ Almanac Best Days Calendar tracks every lunar phase and tells you the best windows for planting, fishing, and outdoor work, day by day. The same tradition that has guided readers for over 200 years.

See the Best Days Calendar

Quick Reference

• What it is: A TikTok trend where two people compare the moon phase on the day they were born. If the two phases visually fit together to form a full moon, the trend says they are compatible.
• Origin: Started by TikTok creator @lexihernandezz in January 2022, went mainstream in March 2023. Hashtag has crossed 430 million views.
• Phases used: The eight standard lunar phases. New, waxing crescent, first quarter, waxing gibbous, full, waning gibbous, last quarter, waning crescent.
• Not the same as astrology: Moon phase compatibility uses date only. Astrological moon signs require birth time and use zodiac, not phase.
• Scientific backing: None. There is zero peer-reviewed evidence the test predicts personality or compatibility.
• Where to look up yours: Free calculators at StarDate (NASA-affiliated) or any moon-phase-by-date tool.

Moon phase compatibility is a TikTok trend in which two people look up the lunar phase on their birthdays and check whether the two phases, drawn next to each other, fit together to form a complete full moon. The hashtag has crossed 430 million views since the test went viral in 2023, which is why a 200-year-old planning publication keeps getting asked about it. Below is what the test actually is, how to find your own birth phase, where it comes from, and what the Almanac thinks of the whole thing.

What Moon Phase Compatibility Actually Means

The premise is simple. Every person was born on a day when the Moon was in one of eight phases. The trend pairs two birth phases against each other. If the two illuminated portions, sketched side by side, complete a full circle, the test says the pair is compatible. If they overlap or leave a gap, the test says they are not. Think of it as a visual puzzle-piece game with the Moon as the pieces.

For example, a partner born under a waxing crescent and a partner born under a waning gibbous would, drawn together, form a roughly complete disk. By the trend’s rules, that pair is a match. Two new moons would not match because two zero-illumination phases cannot complete each other. Neither would two full moons, since there is nothing left to add.

Where the Trend Came From

The compatibility test traces to TikTok creator @lexihernandezz in January 2022. The video was steady but quiet for a year, then surged in March 2023 when a wave of duets and stitches turned it into a meme. The hashtag #moonphasecompatibility has logged more than 430 million views, with over 16 million pieces of content using the underlying filter. Mainstream coverage from Today, NBC News, ABC, and Yahoo all framed the trend as cultural entertainment rather than serious astrology, which is the right frame.

The Eight Phases Used

The test uses the standard astronomical lunar phases:

1. New moon. Moon is between Earth and Sun. Zero percent illuminated. A blank dark disk in the test.

2. Waxing crescent. Up to 49 percent illuminated, lit on the right (Northern Hemisphere). Looks like a D being drawn in.

3. First quarter. Right half lit. A clean half-moon.

4. Waxing gibbous. 51 to 99 percent lit, still growing.

5. Full moon. 100 percent illuminated.

6. Waning gibbous. 99 to 51 percent, shrinking.

7. Last quarter. Left half lit.

8. Waning crescent. 49 percent down to 0, lit on the left, looks like a fading C.

For a longer breakdown of how the cycle works, see our piece on the crescent moon. For the side of the Moon nobody on Earth ever sees, see the far side of the moon. For the side of the Moon nobody on Earth ever sees, see the far side of the moon.

How to Look Up Your Birth Moon Phase

You only need a date. The test does not require birth time, location, or any astrological chart. The calculation is straightforward astronomy.

Free calculators that give you the phase:

1. StarDate Moon Phase tool from McDonald Observatory at the University of Texas. Enter the year and month. NASA-affiliated and accurate.

2. timeanddate.com moon phase archive. Search any date back to 1900.

3. Farmers’ Almanac moon phases calendar. Lists every full moon, new moon, and quarter for the current year.

Once you have a date and an illumination percentage, drop the illumination into one of the eight phase buckets above. That is your birth phase.

Moon Phase Compatibility Is Not Astrology

This is the part most articles get wrong. Astrology and moon phase compatibility are different systems.

Astrological moon sign. Requires your exact date, exact birth time, and exact birth location. Refers to which zodiac sign the Moon occupied at the moment of birth (Aries through Pisces, twelve options). Used by astrologers to talk about emotional temperament.

Moon phase compatibility. Requires only your date. Refers to the Moon’s illumination percentage on that day (eight options). Has nothing to do with the zodiac.

If you have ever heard “I’m a Pisces moon,” that is the astrological moon sign system, not phase compatibility. Two different things, often confused.

The Almanac Take: Honest, Not Snobby

Farmers’ Almanac has used the Moon as a planning calendar since 1818. Plant aboveground crops on a waxing moon, plant root crops on a waning moon, fish on the right phase, that kind of guidance. We treat the Moon as a calendar, not as a fortune-teller.

So here is the honest read on moon phase compatibility. There is no peer-reviewed evidence that the phase the Moon was in on the day you were born has any effect on your personality, your relationships, or who you are compatible with. None. The test is a fun visual game, not a scientific or even a traditional astrological tool. The pairing rules were invented for TikTok in 2022. There is no folkloric tradition behind it.

That said, the puzzle-piece visual is genuinely charming, the underlying lunar mechanics are real and worth knowing, and there is nothing wrong with looking up two birthdays for fun and seeing whether the disks complete each other. Just go in with the right frame. It is entertainment, not insight.

If you want a use of the Moon that has 200 years of tradition behind it, see the Best Days Calendar. That one tells you when to plant tomatoes.

Quick How-To: Run the Test

Step 1. Get both birthdays.

Step 2. Look up each one’s moon phase using the calculators linked above.

Step 3. Sketch the two phases side by side, lit edges facing each other.

Step 4. Check the fit. Together, do they complete a full disk? The trend says yes equals compatible. Gaps or overlaps say no.

Step 5. Take it as the social game it is. Have fun. Read your actual partner.

Frequently Asked Questions

What is moon phase compatibility?

Moon phase compatibility is a TikTok trend that compares the lunar phase from each person’s birth date and checks whether the two phases, drawn side by side, complete a full moon. The hashtag has logged over 430 million views since 2023.

How do I find my moon phase?

Enter your birthday into a free moon-phase calculator like StarDate, timeanddate.com, or the Farmers’ Almanac moon phases calendar. You only need the date, not the time or location. The calculator returns the phase and illumination percentage for that day.

Is moon phase compatibility the same as astrology?

No. Astrological moon signs use the zodiac and require exact birth time and location. Moon phase compatibility uses only the date and refers to the Moon’s illumination percentage. They are different systems, often confused.

Is there scientific evidence behind moon phase compatibility?

No. There are no peer-reviewed studies showing that the lunar phase on a person’s birth date affects personality or relationship compatibility. The test is a viral entertainment trend, not a scientific or traditional astrological tool.

Where did the moon phase compatibility test come from?

TikTok creator @lexihernandezz posted the original test in January 2022. It went viral in March 2023 through duets and stitches, and the hashtag has since crossed 430 million views.

What are the eight moon phases the test uses?

New moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter, and waning crescent. The cycle takes about 29.5 days from one new moon to the next.

Use the Moon for Something Practical

The Farmers’ Almanac Best Days Calendar has tracked the right lunar windows for planting, fishing, and family planning since 1818. Two centuries of tradition, day by day, no fortune-telling required.

See the Best Days Calendar

Quick Reference

• Why we never see it: The Moon is tidally locked to Earth. Its rotation period (27.3 days) matches its orbital period, so the same hemisphere always faces us.
• “Dark side” myth: Both hemispheres get equal sunlight. “Dark” originally meant “unseen,” not “unlit.”
• What we have seen: About 59 percent of the lunar surface, thanks to libration (a slight wobble in the Moon’s orbit).
• First photos: Soviet Luna 3 mission, October 1959.
• First human eyes on it: Apollo 8 crew, December 1968.
• First soft landing: China’s Chang’e 4, January 2019.
• First sample return: China’s Chang’e 6, June 2024.
• Key feature: South Pole-Aitken basin, the largest impact crater in the solar system at 1,550 miles across.

The far side of the moon is the hemisphere humans never saw with our own eyes until December 1968. It is not dark, it is not mysterious in the supernatural sense, and Pink Floyd had nothing to do with naming it. Below is why we always see the same face, what is actually on the side we never see, and the missions that have finally mapped, landed on, and brought rocks back from the side of our nearest neighbor that we cannot see from the kitchen window.

Why We Always See the Same Side

The Moon is tidally locked to Earth. That phrase has a precise meaning. The Moon rotates on its axis exactly once for every full orbit it makes around Earth. Both periods take 27.3 days. The result: the same hemisphere is always pointed at us, and the other half is always pointed away.

This did not happen by accident. Earth’s gravity pulls a little harder on the side of the Moon facing us than the side facing away, which created tidal bulges in the Moon’s rocky body billions of years ago. Over time, that gravitational drag slowed the Moon’s rotation until the spin matched the orbital period. Once the two locked together, they stayed there. The same process is gradually slowing Earth’s rotation; days are getting longer by about 1.7 milliseconds per century.

Tidal locking and lunar phases are different things. Tidal locking determines which face we see. Phases (waxing, full, crescent) determine how much of that visible face is lit by the Sun. For the TikTok trend that pairs people by their birth phase, see moon phase compatibility. The Moon shows the same hemisphere even at new moon, when the lit side has rotated to face away.

“Dark Side” Is a Misnomer

The far side gets exactly as much sunlight as the near side. Both hemispheres go through a 14-day day and a 14-day night every lunar month. When the Moon is in the new-moon phase from our perspective, the far side is in full sunlight. When the Moon is full from our perspective, the far side is in darkness.

So why “dark side”? In the older astronomical literature, “dark” meant “unseen” or “unknown,” not “unlit.” Once humans started flying past the Moon and photographing the far hemisphere, the language gradually shifted. Most working astronomers today say far side. Pink Floyd’s 1973 album, despite popular interpretation, is about mental health, lunacy, and time, not lunar geography.

We Actually See 59 Percent of the Moon

The Moon’s orbit is slightly elliptical and slightly tilted relative to its rotation axis. The combination produces a small wobble called libration that lets observers on Earth peek over the lunar limb (edge) by a few degrees in different directions over the course of a month. Across many cycles, libration adds up. Earth-based observers can eventually see about 59 percent of the lunar surface. That leaves roughly 41 percent of the Moon truly invisible from Earth.

First Photos: Soviet Luna 3, October 1959

The Soviet Luna 3 spacecraft swung past the Moon on October 7, 1959, carrying a small dual-lens camera, an automatic film-development system, and a scanner that converted negatives into radio signals beamed back to Earth. The 29 photographs returned were grainy but historic. They showed for the first time the hemisphere humans had never seen. The far side, the photos revealed, looked profoundly different from the near side. Far fewer dark plains. Far more craters. Soviet scientists named major features in the data, and several names (Mare Moscoviense, the Sea of Moscow) are still in use.

First Human Eyes: Apollo 8, December 1968

Frank Borman, James Lovell, and William Anders became the first humans to see the lunar far side with their own eyes when Apollo 8 entered lunar orbit on December 24, 1968. Anders described the surface as “a vast, lonely, forbidding expanse of nothing.” On the same mission, looking the other direction, Anders took the famous Earthrise photograph. The first humans ever to see Earth as a whole planet were also the first to see the lunar far side.

First Landing: China’s Chang’e 4, January 2019

For 50 years after Apollo 8, no spacecraft had touched the far side. The challenge is not landing technology. The challenge is communication. Direct radio signals between Earth and the lunar far side are blocked by the Moon itself. Any far-side mission requires a relay satellite parked in a position where it can see both Earth and the lunar far side at the same time.

China’s Chang’e 4 spacecraft made the first soft landing on the far side on January 3, 2019, in the Von Karman crater inside the South Pole-Aitken basin. It used a relay satellite, Queqiao, parked at the Earth-Moon L2 Lagrange point, to bounce signals between Earth and the lander. The Yutu-2 rover then drove away from the lander and continued exploring. Yutu-2 was still operational years later, the longest-running rover in lunar history.

First Sample Return: China’s Chang’e 6, June 2024

Chang’e 6 returned to Earth on June 25, 2024, carrying about 1.93 kilograms (roughly 4.3 pounds) of rock and soil collected from the South Pole-Aitken basin on the far side. It was the first sample return from the lunar far side in the history of space exploration. Initial analysis is rewriting the geological history of the Moon, including the timing of late lunar volcanism on the far hemisphere.

The Geology Differs From the Near Side

The two hemispheres look different because they are different.

Crust thickness. The far-side crust averages about 50 kilometers thick. The near-side crust averages about 30 kilometers. Why is still debated; one leading theory involves a giant impact early in lunar history that thinned one hemisphere.

Maria coverage. “Maria” are the dark, basaltic plains that form the man-in-the-moon face. They cover about 31 percent of the near side and only about 1 percent of the far side. Thicker far-side crust prevented underground basalt from reaching the surface, so the far side stayed cratered and rugged instead of getting flooded with lava.

Crater density. The far side has noticeably more craters per square kilometer, partly because it had no widespread volcanic resurfacing to erase the older impact record.

South Pole-Aitken: The Biggest Crater in the Solar System

The far side hosts the largest confirmed impact crater in our entire solar system. The South Pole-Aitken basin is roughly 2,500 kilometers (1,550 miles) across and 8 kilometers (5 miles) deep at its center. It formed roughly 4.3 billion years ago. NASA gravity-mapping data has detected a dense mass beneath the basin, possibly the metallic core of the asteroid that produced the impact, that is roughly five times larger than the Big Island of Hawaii.

Why the Far Side Matters for Future Exploration

Two reasons. First, the lunar far side is shielded from all of Earth’s radio noise. That makes it the best location in the inner solar system for sensitive radio astronomy. NASA’s Lunar Crater Radio Telescope concept proposes to suspend a 1-kilometer-wide wire mesh inside a far-side crater, creating the largest radio telescope ever built and one positioned to listen for signals from the universe’s earliest era, the cosmic dark ages.

Second, the far side hosts the South Pole-Aitken basin, which contains some of the deepest exposed rocks on the Moon. Sampling them gives planetary scientists access to the lunar interior without having to drill kilometers down. NASA’s Artemis program plans to land astronauts near the lunar south pole, and several future Chinese missions target the far side specifically.

Frequently Asked Questions

Why do we always see the same side of the moon?

The Moon is tidally locked to Earth. Its rotation period (27.3 days) matches its orbital period exactly, so the same hemisphere always faces us. Earth’s gravity slowed the Moon’s rotation over billions of years until the two periods synchronized.

Is the far side of the moon dark?

No. Both hemispheres receive equal sunlight. “Dark” originally meant “unseen” or “unknown” in older astronomical writing, not “unlit.” When the Moon looks new from Earth, the far side is in full sunlight; when the Moon is full from Earth, the far side is in darkness.

What was the first photo of the far side of the moon?

The Soviet Luna 3 spacecraft took the first photographs of the far side on October 7, 1959. The 29 grainy images showed a hemisphere with far fewer dark plains and far more craters than the near side.

Has anyone landed on the far side of the moon?

No humans have. China’s robotic Chang’e 4 spacecraft made the first soft landing on January 3, 2019, in the Von Karman crater. China’s Chang’e 6 returned the first far-side soil samples to Earth on June 25, 2024.

What is the largest crater on the moon?

The South Pole-Aitken basin on the lunar far side. It measures about 2,500 kilometers (1,550 miles) across and 8 kilometers (5 miles) deep, making it the largest confirmed impact crater in the solar system. It formed approximately 4.3 billion years ago.

How much of the moon can we see from Earth?

About 59 percent of the lunar surface over time, thanks to a wobble called libration that lets us peek slightly past the lunar edge in different directions. The remaining 41 percent of the Moon is truly invisible from Earth without spacecraft.

Track the Moon You Can See

The far side of the Moon is for spacecraft. The near side has been guiding planters and planners for over 200 years. The Farmers’ Almanac Best Days Calendar puts every phase, name, and best window in your hand.

See the Best Days Calendar

Quick Reference

• Indoor home (general): 30 to 50 percent. ASHRAE and EPA consensus.
• Sleep, asthma, allergies: 30 to 50 percent. Stay below 50 to suppress dust mites and mold.
• Hardwood floors and furniture: 35 to 55 percent.
• Pianos and acoustic guitars: 40 to 50 percent.
• Houseplants: 40 to 60 percent.
• Babies and infants: 40 to 60 percent.
• Cigar humidor: 70 percent.
• Outdoor comfort: Below 30 percent feels dry, 30 to 50 comfortable, 50 to 65 OK, 65 to 80 sticky, above 80 oppressive.
• Mold risk threshold: 65 percent and above. Mold can germinate within 24 to 48 hours.

The right indoor relative humidity sits between 30 and 50 percent, per EPA and ASHRAE consensus. That single window covers most household concerns: comfort, asthma, dust mites, mold, hardwood floors, and electronics. A few uses, like cigar storage at 70 percent or greenhouse plants at 50 to 70, sit outside that band. Below is the full reference chart, the dew-point comfort table, how to measure, and how to fix the air when the meter reads too high or too low.

What Relative Humidity Actually Measures

Relative humidity (RH) is the ratio, expressed as a percentage, of how much water vapor the air is currently holding to the maximum it could hold at the current temperature. Warm air can hold more water vapor than cold air, which is why summer feels muggier even when the absolute amount of moisture has not changed.

Three other terms get used in weather and HVAC work and should not be confused. Absolute humidity is the actual mass of water vapor per cubic meter of air, not a ratio. Specific humidity is the mass of water vapor per kilogram of total air. Dew point is the temperature at which the air would become 100 percent saturated. Dew point does not change as air temperature changes, which is why meteorologists prefer it for comparing comfort across different temperatures.

Indoor Relative Humidity by Use Case

General home comfort: 30 to 50 percent. ASHRAE Standard 55 and EPA’s Indoor airPLUS guidance both target this band. Below 30 produces dry skin, sore throats, static shocks, and respiratory irritation. Above 50 starts encouraging dust mite multiplication and mold growth.

Bedroom and sleep: 30 to 50 percent. Sleep researchers and HVAC engineers agree on the same band. Around 45 percent is a good single-target setting if your humidifier or dehumidifier offers one.

Asthma and allergies: ideally below 50 percent. Dust mites cannot survive below 50 percent humidity for extended periods. Mold growth stalls below 60 percent. Both are major asthma triggers. The American Lung Association recommends 30 to 50 percent for sufferers.

Hardwood floors and furniture: 35 to 55 percent. Wood expands as humidity rises and contracts as it falls. Sudden swings cause cupping, gapping, and joint failure. Manufacturers usually warranty installation only within this range.

Pianos: 40 to 50 percent (constant). Steinway and Yamaha both publish this band. A piano hates change more than it hates a single value.

Acoustic guitars: 45 to 55 percent. Lower humidity cracks the soundboard. Higher humidity lifts bridges.

Houseplants: 40 to 60 percent. Tropical plants prefer the high end. Cacti and succulents thrive at the low end. Most common houseplants are happy at 50.

Babies and infants: 40 to 60 percent. Pediatric guidance from the American Academy of Pediatrics. Reduces airway dryness and viral transmission.

Computer rooms and electronics: 30 to 50 percent. Data centers tighten this to 45 to 55 percent. Below 30 invites static discharge. Above 70 risks condensation.

Cigar humidor: 70 percent. The traditional 70/70 rule (70 percent RH at 70 degrees Fahrenheit). Below 65 dries the cigar; above 75 invites mold.

Greenhouse: 50 to 70 percent. Most cultivars peak at 60. For outdoor plants that handle low-humidity dry climates, see our list of drought tolerant plants.

Outdoor Comfort by Relative Humidity

Outdoor comfort is a function of both temperature and humidity, but at moderate temperatures, RH alone is a useful guide:

Below 30 percent. Dry. Cracked skin, dehydration risk, static. Common in the desert Southwest and during winter indoor heating.

30 to 50 percent. Comfortable. The target band for both indoor and outdoor moderate temperatures.

50 to 65 percent. OK. Slightly humid but tolerable.

65 to 80 percent. Sticky. Sweat does not evaporate efficiently, and perceived temperature climbs.

Above 80 percent. Oppressive. Heat illness risk rises sharply when paired with temperatures above 85 degrees.

Dew Point Comfort Reference

Meteorologists prefer dew point because it is unaffected by temperature swings. Use this as the cleaner outdoor-comfort guide.

Below 50 degrees Fahrenheit. Dry, very pleasant. Common in spring, fall, and high-altitude summer.

50 to 55 degrees. Comfortable for most people.

55 to 60 degrees. Comfortable to slightly humid.

60 to 65 degrees. Noticeably sticky. Common Southeast summer afternoon.

65 to 70 degrees. Oppressive. Most people are uncomfortable.

Above 70 degrees. Dangerous when paired with high temperatures. Heat-illness risk for outdoor activity, athletes, elderly, and infants.

How to Measure Indoor Humidity

The instrument is called a hygrometer. Four common types:

Analog hygrometer. Dial gauge. Inexpensive, attractive, accurate to within about 5 percent. Needs occasional calibration with the salt-test method.

Digital hygrometer. LCD readout, often combined with a thermometer. Accurate to within 2 to 3 percent. Most cost under $20.

Capacitive sensor (in smart thermostats). Many Nest, Ecobee, and similar thermostats display indoor RH. Accurate enough for everyday use.

Dew-point meter. Used by HVAC pros. Reports both RH and dew point.

Placement. Center of the room, away from windows, exterior walls, and HVAC vents, about chest height. Avoid the kitchen and bathroom unless those rooms are what you are measuring.

How to Lower Indoor Humidity

Air conditioning. A working AC removes 5 to 10 percent humidity per hour at typical settings. Make sure the drain pan is clear.

Portable dehumidifier. A 30-pint unit handles a typical 1,500-square-foot home. Empty the tank or run a hose to a drain.

Bath and kitchen exhaust fans. Run for 15 to 20 minutes after a shower or boiling pasta. Single most overlooked humidity source in many homes.

Ventilation. Open windows when outdoor air is drier than indoor.

Fix leaks and drainage. A wet basement or crawlspace pulls room RH up. Address the moisture source first.

How to Raise Indoor Humidity

Humidifier. Ultrasonic units run quietly and produce cool mist. Evaporative units are usually larger but easier to clean. Aim for the bedroom or main living area.

Houseplants. Each adds a small amount of RH through transpiration. A grouping of five to seven plants noticeably affects a small room.

Bowls of water near heating vents. Old technique, still works.

Run the bathroom fan less. Shower steam in winter is a free humidity boost.

Whole-house humidifier. Installed on the furnace. Best option for very dry winter climates.

Health Implications of Wrong Humidity

Too low (below 30 percent). Cracked skin, sore throat, nosebleeds, increased flu-virus survival in the air, dry-eye symptoms, static shocks.

Too high (above 60 percent). Mold germination within 24 to 48 hours, dust mite populations climbing 1.5 to 3 times, allergen sensitization, condensation on cold windows, musty smell, peeling paint.

Mold threshold: 65 percent. Above this, mold can germinate on any surface where dust and organic material exist.

Seasonal and Climate Context

Outdoor RH varies by climate zone. The desert Southwest can sit at 10 to 20 percent in summer afternoons. The Gulf Coast can sit at 75 to 90 percent in summer. Midwestern winters drop indoor RH to 15 to 25 percent because cold outside air, even if it was humid, holds little water and gets dry once heated.

Winter target: 30 to 40 percent. Above 40 in winter risks condensation on cold window glass.

Summer target: 40 to 50 percent. Mold and dust-mite suppression matters more in summer.

Frequently Asked Questions

What is the ideal indoor relative humidity?

30 to 50 percent. ASHRAE and the EPA both recommend this band for general home comfort, asthma management, mold prevention, and dust-mite suppression. Aim for around 45 percent if your humidifier or dehumidifier has a single setting.

What humidity is best for sleep?

30 to 50 percent in the bedroom. Around 45 percent is the most commonly cited single-target value. Lower than 30 dries airways and skin; higher than 50 risks dust mites.

What humidity is best for asthma?

Below 50 percent. The American Lung Association recommends 30 to 50 percent for asthma sufferers. Dust mites, a common trigger, cannot survive below 50 percent for long, and mold growth slows below 60 percent.

What is the difference between relative humidity and dew point?

Relative humidity is a percentage that depends on the current air temperature. Dew point is a temperature, not a percentage, and stays the same even when air temperature changes. Meteorologists prefer dew point because it is a stable measure of how humid the air actually feels.

At what humidity does mold grow?

Mold can germinate within 24 to 48 hours when relative humidity stays above 65 percent. Keep indoor humidity below 60 percent to prevent it. The EPA recommends 30 to 50 percent.

What humidity is bad for hardwood floors?

Below 35 percent or above 55 percent. Wood floors expand and contract with humidity, and sudden swings cause cupping, gapping, and joint failure. Manufacturers typically warranty installations only within 35 to 55 percent.

See What the Air Will Do Next Season

Humidity tracks the seasons. Farmers’ Almanac long-range forecasts cover the next two seasons region by region, so you can plan around the air, not just react to it.

View the Long-Range Forecast

Quick Reference

• What it is: A long, narrow corridor of concentrated water vapor moving through the atmosphere, typically 250 to 375 miles wide and over 1,000 miles long.
• How much water: A strong atmospheric river transports more water vapor than the Mississippi River carries on the ground.
• The Pineapple Express: The most famous variety, hauling tropical Pacific moisture from near Hawaii to the West Coast.
• Scale: AR1 (weak/beneficial) through AR5 (exceptional/hazardous), the Ralph scale developed at Scripps Institution of Oceanography.
• How much rain: Roughly 30 to 50 percent of the West Coast’s annual precipitation comes from atmospheric rivers, and 80 percent of West Coast flood damage.
• Worst recent year: Winter 2022-2023 brought 9 consecutive ARs to California, dumping 32 trillion gallons of water and triggering 700+ landslides.

An atmospheric river is a long, narrow corridor of concentrated water vapor that moves through the atmosphere like a river runs through a landscape. The strongest ones can transport more water vapor in a day than the Mississippi River carries on the ground. They are the reason a “Pineapple Express” forecast in California means saturated soil, full reservoirs, mudslides, and headlines for two weeks. Below is what an atmospheric river actually is, the AR1-AR5 scale meteorologists now use to rate them, and why the West Coast lives and dies by them.

What Counts as an Atmospheric River

An atmospheric river is a corridor of moisture in the lower atmosphere, typically 250 to 375 miles wide and 1,000 to 2,000 miles long, fed by evaporation from warm tropical or subtropical oceans. The water moves as vapor (not yet rain) until the corridor reaches land or a mountain range, where it is forced upward, cooled, and condensed into heavy precipitation.

Per NOAA, a strong atmospheric river can transport 7.5 to 15 times the average daily flow of the Mississippi River. That is moisture, not liquid water on the ground; it becomes rain or snow when the river hits the West Coast and runs into the Sierra Nevada or the Cascades.

The Pineapple Express

The Pineapple Express is the most famous and most studied atmospheric river. It originates in the warm Pacific waters near Hawaii, picks up large amounts of tropical moisture, and aims that corridor of water vapor at California, Oregon, Washington, and British Columbia. Pineapple Express events deliver some of California’s heaviest rainfall, the bulk of Sierra Nevada snowpack, and the bulk of the state’s flood disasters.

The AR Scale: AR1 Through AR5

Hurricanes have the Saffir-Simpson scale. Tornadoes have the EF scale. Atmospheric rivers got their own scale in 2019, developed by Marty Ralph and colleagues at the Center for Western Weather and Water Extremes at Scripps Institution of Oceanography. The scale ranks intensity by integrated water vapor transport (IVT) and duration.

AR1 (weak). Primarily beneficial. Helpful rainfall, modest impact.

AR2 (moderate). Mostly beneficial but some hazards.

AR3 (strong). Balanced beneficial and hazardous. Moderate flood risk.

AR4 (extreme). Mostly hazardous. Significant flood risk, dam concerns, mudslides.

AR5 (exceptional). Primarily hazardous. Catastrophic flooding potential. Rare; only a handful per decade.

Why the West Coast Lives by Atmospheric Rivers

Atmospheric rivers deliver between 30 and 50 percent of the West Coast’s annual precipitation, depending on the location and year. For California specifically, the share runs closer to 50 percent. They are also responsible for roughly 80 percent of West Coast flood damage, which is the trade-off. The same storms that fill the reservoirs and the snowpack also fill the rivers and the basements.

The 2017 Oroville Dam Crisis

In February 2017, a sequence of atmospheric rivers dropped enormous volumes of water on Northern California. Inflow into Lake Oroville, the state’s second-largest reservoir, exceeded the design capacity of the main spillway, which then partially failed. The emergency spillway, never used in the dam’s 49-year history, eroded so quickly that authorities ordered an evacuation of 188,000 people downstream. Repair costs ran more than $1 billion. Atmospheric river research after the event found that warming had amplified the AR’s water content by 11 to 15 percent.

Winter 2022-2023: Nine Rivers in a Row

From late December 2022 through mid-January 2023, California was hit by nine consecutive atmospheric rivers in three weeks. The sequence dumped about 32 trillion gallons of water on the state, triggered more than 700 landslides, killed at least 22 people, and produced an estimated $5 to 7 billion in damage. It was also the moment that ended California’s worst multi-year drought on record. ARs both make and break West Coast water years.

Forecasting: AR Recon Aircraft

Since 2016, NOAA, Scripps, and the U.S. Air Force have flown aircraft (WC-130J Hurricane Hunters and Gulfstream IV jets) directly into atmospheric rivers over the open Pacific. The crews drop instrument packages called dropsondes through the corridor to measure water vapor, wind, and temperature in real time. The program, AR Recon, has improved 3-day West Coast precipitation forecasts by about 12 percent. The same technique has been applied to hurricane forecasting since the 1940s; ARs got the treatment 75 years later.

Climate Trends

Warmer air holds more water vapor, about 7 percent more for every 1 degree Celsius of warming, per the Clausius-Clapeyron relation. Atmospheric rivers, by definition, are vapor-transport features. As the Pacific warms, the strongest ARs are expected to carry more water and produce heavier rainfall. Federal climate projections estimate $2.3 to $3.2 billion in annual AR-related damages by 2090 if current warming trajectories hold.

For broader context on the seasonal climate cycles that influence whether a West Coast winter is wet or dry, see our explainers on El Nino and La Nina.

Atmospheric Rivers Outside the West Coast

Most US atmospheric river research is West Coast focused, but the phenomenon is global. The United Kingdom regularly receives atmospheric rivers from the subtropical Atlantic. The Pacific Northwest of Canada gets the same Pineapple Express that feeds California. East Asia gets ARs that originate over the western Pacific and tropical China Sea. Even the East Coast gets occasional ARs, though they are usually less intense and overshadowed by hurricanes and Nor’easters in the public conversation.

Frequently Asked Questions

What is an atmospheric river?

An atmospheric river is a long, narrow corridor of concentrated water vapor in the lower atmosphere, typically 250 to 375 miles wide and over 1,000 miles long. A strong atmospheric river can transport more water vapor in a day than the Mississippi River carries on the ground.

Why is California so affected by atmospheric rivers?

California sits at the receiving end of the Pacific atmospheric river corridor. Tropical and subtropical Pacific moisture is forced upward by the Sierra Nevada and Coast Ranges, condensing into heavy rain and snow. Roughly 50 percent of California’s annual precipitation and 80 percent of West Coast flood damage comes from atmospheric rivers.

What is the Pineapple Express?

The Pineapple Express is the most well-known atmospheric river, originating near Hawaii and aimed at the US West Coast. It picks up tropical Pacific moisture and delivers heavy rainfall and Sierra Nevada snowpack to California, Oregon, and Washington.

How are atmospheric rivers measured?

The AR scale, developed in 2019 by Marty Ralph at Scripps Institution of Oceanography, ranks atmospheric rivers from AR1 (weak, primarily beneficial) to AR5 (exceptional, primarily hazardous). The ranking uses integrated water vapor transport and duration.

Are atmospheric rivers becoming more intense?

Research indicates yes. Warmer air holds more water vapor (roughly 7 percent more per 1 degree Celsius of warming), so the strongest atmospheric rivers carry more water and produce heavier rainfall in a warmer climate. Federal projections estimate $2.3 to $3.2 billion in annual AR-related damages by 2090 if current warming trajectories continue.

What was the worst recent atmospheric river event?

Winter 2022-2023 brought California 9 consecutive atmospheric rivers over 3 weeks, dumping 32 trillion gallons of water, triggering 700+ landslides, killing 22 people, and causing $5 to 7 billion in damage. The 2017 Oroville Dam crisis was driven by a similar AR sequence and forced 188,000 people to evacuate.

See What’s Coming for the West Coast

Atmospheric rivers run on a season-scale cycle. Farmers’ Almanac long-range forecasts cover the West Coast region by region, so you can see what kind of winter to plan for before the watches start.

View the Long-Range Forecast

Quick Reference

• Category 1: 74 to 95 mph. Some damage. Roofs, gutters, siding.
• Category 2: 96 to 110 mph. Extensive damage. Major roof and siding failure, mass tree damage.
• Category 3 (major): 111 to 129 mph. Devastating damage. Well-built homes lose roof decking.
• Category 4 (major): 130 to 156 mph. Catastrophic damage. Severe wall and roof failure.
• Category 5 (major): 157 mph or higher. Catastrophic. A high percentage of framed homes destroyed.
• Created: 1971 by Herbert Saffir (engineer) and Robert Simpson (NHC director). Wind-only since 2009.
• Major hurricane: Category 3 or higher. Causes the bulk of US hurricane damage.

The Saffir-Simpson Hurricane Scale is the 1-to-5 ranking that puts a number on a hurricane’s wind damage potential. It is announced before every Atlantic landfall, quoted in every storm forecast, and the source of the phrase “Category 5.” Below is what each category means, the famous storms that defined them, and what the scale does and does not measure.

How the Scale Was Built

Civil engineer Herbert Saffir was working on UN-funded low-cost housing in 1969 when he tried to estimate how much wind a building had to survive. He sketched a 1-to-5 scale based on damage thresholds, modeled on the Mercalli earthquake scale. Robert Simpson, then director of the National Hurricane Center, added storm surge and pressure data and made the scale public in 1971. It became the public-facing US hurricane ranking standard by 1973.

In 2009 the National Hurricane Center revised the scale to a wind-speed-only system, called the Saffir-Simpson Hurricane Wind Scale. The change took effect for the 2010 Atlantic season. Storm surge and pressure dropped out because surge depends heavily on local geography and pressure correlations were inconsistent. The category number now reflects only the maximum sustained 1-minute wind speed at 33 feet above ground.

Below the Scale: Tropical Depression and Tropical Storm

Before a system reaches Category 1, it has two earlier stages. Tropical depression: sustained winds of 38 mph or less. Tropical storm: sustained winds of 39 to 73 mph. The Atlantic basin gives a tropical storm its name (the next on the rotating list) once it crosses the 39 mph threshold. A storm only becomes a hurricane at 74 mph.

The Five Categories

Category 1: 74 to 95 mph. “Very dangerous winds will produce some damage,” per the National Hurricane Center. Loose shingles peel off, vinyl siding cracks, large branches snap, and shallow-rooted trees come down. Power outages can last a day or two. Examples: Hurricane Hanna (2020), Hurricane Isaias (2020 at landfall).

Category 2: 96 to 110 mph. “Extensive damage.” Major roof and siding damage, mass tree damage, road blockages, multi-week power outages possible. Hurricane Frances (2004) and Hurricane Sally (2020) hit the Gulf Coast at Category 2.

Category 3: 111 to 129 mph. First “major” classification. “Devastating damage.” Well-built framed homes can lose roof decking. Trees snap in large numbers. Electricity and water outages from days to weeks. Hurricane Katrina (2005) struck the Mississippi-Louisiana coast as a strong Category 3 with 125 mph winds.

Category 4: 130 to 156 mph. “Catastrophic damage.” Severe damage to well-built homes, with loss of most of the roof structure and exterior walls. Most trees snapped or uprooted. Power outages last weeks to months. Hurricane Ian (2022, 150 mph), Hurricane Helene (2024, 140 mph at landfall), Hurricane Charley (2004), Hurricane Harvey (2017 at peak).

Category 5: 157 mph or higher. “Catastrophic damage.” A high percentage of framed homes are destroyed. Power outages last months. Some areas are uninhabitable for weeks or longer. Hurricane Andrew (1992, 165 mph at landfall over Homestead), Hurricane Michael (2018, 160 mph over Mexico Beach, FL), Hurricane Allen (1980, briefly 190 mph), Hurricane Wilma (2005, 185 mph at peak).

“Major Hurricane” Means Category 3 or Higher

The phrase has a specific NOAA definition. A “major hurricane” is any storm at Category 3 or above (111 mph winds and up). Major hurricanes account for the majority of US hurricane damage even though they make up a minority of total Atlantic storms. The annual NOAA hurricane outlook always announces an expected number of named storms, hurricanes, and major hurricanes separately.

What the Scale Does Not Measure

The Saffir-Simpson scale is a wind-speed scale. It does not score:

Storm surge. A Category 1 storm with a wide, slow track and a shallow coastline can produce a surge as deadly as a Category 4. Hurricane Sandy (2012) made landfall as a post-tropical cyclone, technically below hurricane strength, and still produced a 14-foot surge in New York Harbor.

Rainfall. Hurricane Harvey in 2017 was a Category 4 at landfall, then weakened to a tropical storm. The damage came from 60 inches of rain over Houston, not from the wind. Hurricane Helene’s 2024 catastrophic flooding in western North Carolina, far inland, was a similar story.

Tornado activity. Most Atlantic hurricanes spawn tornadoes during landfall. The scale does not reflect this.

Storm size. Hurricane Andrew was a small, intense storm. Hurricane Sandy was massive but lower-intensity. The scale captures only the peak wind speed, not the area affected.

For the broader weather picture during hurricane season, see our explainers on El Nino and La Nina, and the atmospheric river piece for the West Coast counterpart.

Sustained Wind vs Wind Gusts

The category number reflects sustained wind speed (1-minute average at 33 feet). Wind gusts during the same hurricane can be 10 to 25 percent higher. A Category 3 storm with 125 mph sustained winds can produce gusts of 150 mph or more. NOAA reports both numbers in advisories, but the category itself is fixed to sustained.

Why There Is No Category 6

Some scientists have proposed a Category 6 for storms above 192 mph, citing increasing ocean heat content and more frequent extreme intensities. The National Hurricane Center has not adopted the change. The argument against: at Category 5, framed homes are already destroyed and the area is uninhabitable for weeks or months, so a Category 6 would not change emergency response. The category structure exists to drive public action, not to win academic debates. For now, 157 mph and up is the open-ended top of the scale.

Frequently Asked Questions

What is the Saffir-Simpson Hurricane Scale?

A 1-to-5 ranking of hurricane intensity by maximum sustained wind speed. Category 1 begins at 74 mph; Category 5 begins at 157 mph. Engineer Herbert Saffir and NHC director Robert Simpson developed it in 1971. The current wind-only version took effect in 2010.

What wind speed makes a Category 5 hurricane?

157 mph or higher sustained winds. The category is open-ended; there is no upper limit. Hurricane Allen in 1980 reached an estimated 190 mph briefly, and Hurricane Wilma in 2005 hit 185 mph at peak intensity.

What is a “major” hurricane?

NOAA defines a major hurricane as Category 3 or higher (111 mph winds or above). Major hurricanes cause the majority of US hurricane damage even though they are a minority of total storms.

What did the Saffir-Simpson scale used to measure?

The original 1971 scale combined wind speed, central pressure, and storm surge. The 2009 revision dropped pressure and surge because they correlate poorly with wind damage and depend heavily on local coastline shape. Since 2010 it has been wind-only.

Why is there no Category 6?

The National Hurricane Center has not added one. The argument: at Category 5, framed homes are already destroyed and an area is uninhabitable for months. A Category 6 would not change emergency response. The scale exists to drive public action, not to win academic debates.

Are wind gusts higher than the category indicates?

Yes. Gusts during a hurricane are typically 10 to 25 percent higher than the sustained 1-minute average that defines the category. A Category 4 with 140 mph sustained winds can gust above 170 mph.

Plan Around Hurricane Season

Farmers’ Almanac long-range forecasts cover the Gulf and Atlantic months ahead. Know what kind of season is coming before the storm names start.

View the Long-Range Forecast