Louisiana ranks first under the composite morning-and-afternoon relative humidity method used in this article, while Arizona ranks last. That does not make either state the universal winner or loser under every humidity metric. Alaska can rank much higher when annual relative humidity is emphasized, while dew point better reflects how muggy warm outdoor air feels. This article explains the differences, provides a full 50-state RH ranking, and shows why other methods may produce a different order.
The Quick Answer: Most Humid and Least Humid States at a Glance
Here's how the states rank when morning and afternoon relative humidity are weighted equally. Each state was ranked separately by its morning RH and afternoon RH, and the two ranks were averaged to create a composite score. NOAA publishes station-level readings rather than an official 50-state ranking, so the order shown here is a derived ranking, not an official NOAA list.
| Most-Humid Rank | State | Composite Score | Least-Humid Rank | State | Composite Score |
|---|---|---|---|---|---|
| 1 | Louisiana | 5.75 | 1 | Arizona | 50.00 |
| 2 | Florida | 8.50 | 2 | Nevada | 48.75 |
| 3 | Michigan | 8.75 | 3 | New Mexico | 48.25 |
| 3 | Minnesota | 8.75 | 4 | Colorado | 47.00 |
| 3 | Wisconsin | 8.75 | 5 | Utah | 46.00 |
| 6 | Iowa | 10.00 | 6 | Idaho | 44.50 |
| 7 | Illinois | 11.75 | 6 | Wyoming | 44.50 |
| 7 | Indiana | 11.75 | 8 | California | 42.75 |
| 7 | North Dakota | 11.75 | 9 | Montana | 42.25 |
| 10 | West Virginia | 12.25 | 10 | Maryland | 36.75 |
Ranking method: Each state was ranked separately by morning RH and afternoon RH. The two ranks were then averaged to create a composite RH rank score. Lower scores rank higher. States with the same composite score share the same overall rank.
This is not the only way to rank humidity, and it will not match every list published online. Results change when a source uses different stations, observation times, averaging periods, or ranking formulas.
This pushes Alaska to the top in RH-based rankings — cold air there can remain close to saturation while containing less water vapor than warm Gulf Coast air. Dew point tells a different story, favoring places like Hawaii and Florida instead, since their air holds more actual moisture even at a similar saturation percentage. The two metrics use separate datasets and shouldn't be treated as interchangeable — here's the method behind each number.
How the Composite RH Score Was Calculated
This is a derived ranking, not an official NOAA list. The morning and afternoon RH values were ranked separately from highest to lowest. Tied values received average ranks, and the two rankings were then combined using the following formula:
Composite RH Rank Score = (Morning RH Rank + Afternoon RH Rank) ÷ 2
A lower composite score indicates a higher overall position. States with identical composite scores share the same rank. The available state-level RH values were rounded to whole percentages before this recalculation, so the table contains more ties than a calculation based on unrounded weather-station data. The score is a ranking value, not a humidity percentage or a 24-hour daily average.
How These Rankings Are Actually Calculated
Different rankings disagree because they measure different things. Before crowning a single state, it helps to pin down what "humid" is actually measuring: RH, dew point, or a specific time of day. Each one can produce a different winner.
Relative Humidity: A Percentage, Not a Moisture Count
Relative humidity is the water vapor in the air, shown as a percentage of the max the air could hold at that temperature. It's a ratio, not a moisture count, and that's where most of the confusion starts.
Warm air holds far more water vapor than cold air, so the same RH percentage means something different depending on temperature. Cold air near its saturation point can hit a high RH reading while holding very little actual moisture.
A 90% RH reading isn't automatically miserable; what counts as high humidity depends on the temperature riding along with that number.
Dew Point: A Better Measure of How Air Actually Feels
Dew point is the temperature air must cool to before it saturates. Unlike RH, it doesn't shift with the current temperature; it only moves when actual moisture changes, which makes it a truer read on how sticky the air feels.
That fixes a few contradictions in these rankings. Alaska can post a sky-high RH reading without feeling tropical, because its cold air sits close to saturation while holding little moisture in absolute terms.
Florida and Louisiana can show a lower RH on a given afternoon and still feel far more oppressive, since their warm air carries more water vapor at that same saturation ratio. Dew points above roughly 65°F read as muggy, past 70°F as oppressive. Common on the Gulf Coast in summer, rare out west or in Alaska.
Why Morning and Afternoon Readings Differ
RH runs highest in early morning, when overnight cooling pushes air close to saturation, and lowest in the afternoon, as rising temperatures let air hold more moisture without saturating. A single "daily average" can hide a big morning-to-afternoon swing.
That's also why timing matters when comparing states. NOAA's Comparative Climatic Data lists selected morning and afternoon observations separately, and the local standard observation times vary by region and time zone. In the published table, morning observations range from approximately 4 a.m. to 9 a.m., while afternoon observations range from noon to 5 p.m. Any derived ranking should therefore identify the observations used and explain exactly how the two columns were combined.
Where This Data Comes From, and What It Doesn't Capture
These rankings come from readings at National Weather Service stations, compiled in NOAA's Comparative Climatic Data through the National Centers for Environmental Information.
NOAA doesn't publish one official "most humid state" list, just station-level averages. Any 50-state ranking, this one included, sits on top of that raw data.
A few limits are worth flagging.
- Each state's number usually comes from one or a handful of long-record stations, not every station in the state so it can smooth over real gaps between coastal, inland, mountain, and urban spots.
- The readings reflect long-term averages, not one specific year, and a ranking built on annual averages shifts depending on whether the dataset blends morning and afternoon or keeps them separate.
That's part of why Alaska tops some lists and ranks lower on others.
Humidity by State: The Complete Ranking
The table below ranks all 50 states by combined morning-and-afternoon RH, using the same NOAA-sourced data as the top/bottom 10 lists above.
| Rank | State | Morning RH | Afternoon RH | Composite Score | Climate Note |
|---|---|---|---|---|---|
| 1 | Louisiana | 88% | 60% | 5.75 | Gulf Coast, humid subtropical |
| 2 | Florida | 86% | 59% | 8.50 | Subtropical peninsula, high dew points |
| 3 | Michigan | 82% | 62% | 8.75 | Great Lakes moisture, cool summers |
| 3 | Minnesota | 82% | 62% | 8.75 | Upper Midwest lakes region |
| 3 | Wisconsin | 82% | 62% | 8.75 | Great Lakes, moist summers |
| 6 | Iowa | 82% | 61% | 10.00 | Corn Belt, summer crop moisture |
| 7 | Illinois | 82% | 60% | 11.75 | Midwest, inland Gulf moisture |
| 7 | Indiana | 82% | 60% | 11.75 | Midwest, Great Lakes influence |
| 7 | North Dakota | 82% | 60% | 11.75 | Northern Plains |
| 10 | West Virginia | 84% | 58% | 12.25 | Appalachian, forested terrain |
| 11 | Missouri | 82% | 59% | 13.75 | Central Plains, Gulf-fed moisture |
| 12 | Alaska | 79% | 70% | 14.00 | Cold climate; high RH in cold air |
| 12 | Mississippi | 89% | 56% | 14.00 | Deep South, Gulf-influenced |
| 14 | Ohio | 81% | 60% | 14.50 | Great Lakes region |
| 15 | Alabama | 86% | 56% | 15.25 | Deep South, humid subtropical |
| 16 | Arkansas | 84% | 56% | 17.00 | Southern Plains, Gulf-influenced |
| 16 | Tennessee | 84% | 56% | 17.00 | Southern Appalachian region |
| 18 | Hawaii | 78% | 62% | 17.75 | Tropical islands, trade-wind moisture |
| 19 | North Carolina | 83% | 56% | 18.00 | Coastal-to-mountain variation |
| 20 | Kentucky | 81% | 58% | 18.50 | Ohio Valley, humid continental |
| 21 | Maine | 78% | 60% | 20.75 | New England coast |
| 22 | Georgia | 85% | 53% | 21.75 | Deep South, warm summers |
| 23 | South Dakota | 79% | 58% | 22.25 | Northern Plains |
| 23 | Washington | 79% | 58% | 22.25 | Pacific Northwest, marine influence |
| 25 | Oklahoma | 80% | 56% | 24.75 | Southern Plains, Gulf moisture influence |
| 26 | Oregon | 78% | 57% | 27.00 | Strong coastal and inland variation |
| 26 | Pennsylvania | 78% | 57% | 27.00 | Mid-Atlantic, humid continental |
| 28 | New York | 76% | 58% | 27.50 | Coastal-to-inland variation |
| 28 | South Carolina | 82% | 52% | 27.50 | Southeastern coastal climate |
| 28 | Vermont | 76% | 58% | 27.50 | Inland New England |
| 31 | Nebraska | 80% | 54% | 28.75 | Central Plains |
| 32 | Virginia | 79% | 55% | 29.50 | Coastal Plain to Piedmont variation |
| 33 | New Hampshire | 80% | 53% | 30.50 | New England climate |
| 33 | Texas | 80% | 53% | 30.50 | Humid Gulf Coast to arid West Texas |
| 35 | Kansas | 79% | 54% | 31.00 | Central Plains |
| 36 | Massachusetts | 75% | 57% | 31.25 | New England coast |
| 37 | Delaware | 78% | 55% | 32.00 | Mid-Atlantic coast |
| 38 | Connecticut | 76% | 56% | 32.25 | Southern New England |
| 39 | New Jersey | 76% | 54% | 36.25 | Mid-Atlantic coast |
| 39 | Rhode Island | 75% | 55% | 36.25 | Southern New England coast |
| 41 | Maryland | 77% | 53% | 36.75 | Chesapeake Bay region |
| 42 | Montana | 70% | 49% | 42.25 | Northern Rockies, dry continental |
| 43 | California | 68% | 49% | 42.75 | Coastal, valley, mountain, and desert variation |
| 44 | Idaho | 67% | 45% | 44.50 | Mountain West, semi-arid |
| 44 | Wyoming | 64% | 46% | 44.50 | High Plains, dry and windy |
| 46 | Utah | 63% | 43% | 46.00 | Great Basin, arid and high elevation |
| 47 | Colorado | 59% | 39% | 47.00 | Rocky Mountains, high elevation |
| 48 | New Mexico | 57% | 34% | 48.25 | High desert, arid |
| 49 | Nevada | 57% | 32% | 48.75 | Great Basin Desert |
| 50 | Arizona | 52% | 28% | 50.00 | Sonoran Desert, low afternoon RH |
Source: Recalculated from the state-level morning and afternoon RH values shown in the original dataset. Morning and afternoon values were ranked separately using average ranks for ties, then combined into a composite score. Because the available RH values were rounded to whole percentages, the results contain more ties than a calculation based on unrounded station data.
Use the RH columns to see how close each state's air typically sits to saturation at a given time of day, and the climate note as a quick read on whether that saturation comes with real moisture (Gulf Coast, Great Lakes) or not much at all (Alaska, high desert).
Planning a move or sizing equipment for a specific spot? Check city-level data instead; a single state average can cover wildly different regional climates.
The 10 Most Humid States, and What Actually Drives Their Numbers
Rather than ten separate profiles, group them by cause. A Gulf Coast state gets humid for different reasons than a Great Lakes state or Alaska.
Gulf Coast Heat and Moisture: Louisiana, Florida, and Mississippi
Louisiana, Florida, and Mississippi sit near the top because warm Gulf of Mexico water keeps feeding moisture into the regional air, and coastal wetlands add more. Their humid subtropical climates, tropical in parts of Florida, pair long warm seasons with onshore winds pushing that moist Gulf air inland.
Louisiana ranks first in the combined RH ranking used here, but Florida usually posts higher dew points and stickier conditions through summer. Louisiana wins on saturation; Florida wins on actual water vapor, which is what dew point tracks.
Great Lakes Moisture: Michigan, Minnesota, and Wisconsin
Michigan, Minnesota, and Wisconsin land in the top five mostly from moisture pulled off the Great Lakes and their own inland lakes.
Cooler regional temperatures increase RH by definition, cool air needs less added moisture to approach saturation, and summer evaporation off all that open water adds to it.
That high RH ranking doesn't mean these states feel damper than Florida or Louisiana on a normal summer day. Their dew points run lower, so the air hits a high saturation percentage without carrying the same actual moisture load.
The Midwest and "Corn Sweat": Iowa, Illinois, and the Corn Belt
Iowa and Illinois rank high partly from moist air pulled north from the Gulf in warm months, plus rivers, lakes, and soil moisture across the region. Summer crop transpiration adds a real, documented boost.
Corn and soybean plants release water vapor as they cool themselves, a process nicknamed "corn sweat." One acre of corn can push roughly 3,000 to 4,000 gallons of water into the air per day, and millions of acres doing that at once across the Corn Belt in late summer measurably raises local humidity.
Corn sweat is real, but it's a supporting act; Gulf and Great Lakes moisture do most of the work here.
Why Alaska Sometimes Tops the List
Alaska can rank at or near the very top on annual average RH, because cold air needs relatively little water vapor to reach a high saturation percentage.
Its abundant surrounding water, combined with low average temperatures, gives it one of the highest average RH readings of any state, the single highest in some compilations.
That doesn't mean Alaska feels tropical. Its dew points run far lower than the Gulf Coast's, so the air sits close to saturation without holding much actual moisture.
That gap is exactly why some pages put Louisiana first, and others put Alaska first; they're measuring different things, not disagreeing about the weather.
The 10 Least Humid States, and Why They Stay Dry
The driest states cluster for a simple reason: they sit far from major moisture sources, and their climates limit how much water vapor reaches the air in the first place.
The Desert Southwest: Arizona, Nevada, and New Mexico
Arizona, Nevada, and New Mexico rank at or near the bottom because of desert and semi-arid climates. Limited rainfall, distance from Pacific and Gulf moisture, strong year-round sun, and high evaporation all keep moisture low, and dry regional air masses lock the effect in. Arizona and Nevada hold the bottom two spots on most recent datasets.
Elevation and Rain Shadows: Colorado, Utah, and Wyoming
Colorado, Utah, and Wyoming rank low mostly from elevation and inland location. High terrain and mountain rain shadows, where mountains block moist air from reaching the leeward side, combine with desert basins to keep humidity down.
It still changes a lot by season and elevation inside these states; a mountain valley and a high desert basin can post very different readings.
The Northern Rockies, and Why California Needs an Asterisk
Idaho and Montana round out the driest states through continental climate, elevation, and mountain terrain that keeps them far from ocean moisture. California shows up on the dry end too, but it needs more caution than most states here.
Its coastal, valley, mountain, and desert regions have wildly different climates, and one statewide average can't describe any single one of them. Read the table's California figure as directional, not descriptive of the whole state.
Why Different Sources Rank Humidity Differently
The rankings above aren't the only ones out there. Some lists put Alaska first, others put Louisiana first, and city-level lists land somewhere else entirely. That's not a data error; it depends on the metric, stations, and time window.
Three Metrics, Three Different Pictures
|
Metric |
What It Measures |
Best Used For |
|
Relative humidity |
How close the air is to saturation at its current temperature |
Comparing saturation and condensation risk |
|
Average dew point |
The actual amount of moisture in the air |
Comparing how humid conditions actually feel |
|
Morning/afternoon RH |
Relative humidity at a specific time of day |
Comparing daily changes between states |
A ranking built on any one column here produces a different "most humid state" than a ranking built on another, even pulling from the same weather data.
Which Stations Get Counted Changes the Result
Statewide humidity isn't measured everywhere, so a ranking leans hard on which stations get included, whether coastal and inland readings carry equal weight, the observation period used, and if the final number is a simple average or a calculated score. Two sources pulling from the same NOAA archive can still land on a different order.
"Most Humid" Answers Two Different Questions
Someone worried about condensation or mold is really asking about relative humidity. Someone asking how sticky the air feels outside is really asking about dew point, and those two questions don't always point to the same state.
NOAA-based rankings put Alaska right alongside Louisiana and Mississippi for highest average RH, even though only the Gulf Coast states actually feel tropical. In New Orleans, morning RH tops 90% most summer days, yet the dew point behind that number stays well under what the Gulf Coast hits on its muggiest days.
July dew point maps show the same split geographically. Gulf Coast states like Louisiana, Mississippi, and Florida commonly average above 70°F, while much of the interior Mountain West sits in the 20s and 30s for that same month.
What Makes Some Regions More Humid Than Others
A handful of geographic factors decide how much moisture reaches a state's air.
- Oceans and large lakes supply the moisture in the first place. The Gulf of Mexico, the Atlantic and Pacific coasts, and the Great Lakes evaporate huge volumes of water that prevailing winds carry inland.
- Temperature and seasonal wind patterns decide what that moisture does next. Warmer air holds more of it, and seasonal wind shifts push moist air north from the Gulf in summer and dry continental air south from Canada in winter.
- Elevation, deserts, and rain shadows work against it. High terrain and mountain ranges block moist air from reaching interior basins, a big reason the Mountain West and Southwest stay dry no matter the season.
- Vegetation and agriculture add a smaller push. Forests, wetlands, and irrigated cropland release moisture through evapotranspiration, stacking onto whatever the local geography already supplies during the growing season.
Why a Statewide Average Doesn't Describe Every Location in That State
One number for an entire state can hide a lot. Coastal and inland areas of the same state often see very different humidity, and so do mountains and valleys, cities and rural areas, mornings and afternoons.
Season matters too; a summer humidity profile can look nothing like winter, and any single ranking reflects a long-term average, not this week's weather.
Florida's coastlines run more humid than its interior. Texas extends to a humid Gulf Coast and an arid western desert inside one state line. California's coastal, valley, mountain, and desert regions each carry their own humidity profile.
Comparing specific cities instead, Houston versus Miami, say, is a related but separate question this article doesn't cover, since city rankings use their own station data and land on their own order.
How Humid Outdoor Air Can Affect a Home
Humid outdoor air raises a home's indoor moisture load in a few specific ways:
- through gaps and leaks in the building envelope
- through basements and crawl spaces where ground moisture and outdoor air both get in
- through warm humid air hitting cooler indoor surfaces and condensing
- through wet weather paired with bad drainage around the foundation
Living in a humid state doesn't mean a home runs humid inside; good ventilation, drainage, and air sealing keep plenty of Louisiana and Florida homes well under control.
The reverse holds too: homes in Arizona or Colorado can pick up leaks, foundation moisture, or condensation that has nothing to do with the state average.
Check the Number Before You Buy Anything
The EPA's indoor humidity guidelines put the healthy range at 30–50%, with 60% as the ceiling before mold risk climbs, and a $15 hygrometer tells you in minutes if your home sits inside that range.
If it doesn't, the fix usually isn't a stronger fan. It's picking a unit sized for the square footage, the same logic behind choosing the right dehumidifier for your space.
For whole-house moisture, the AlorAir® Sentinel WHD 100 pulls 90 pints a day and covers up to 2,300 sq. ft., with a fresh-air function built for steady, whole-building control. For a crawl space or basement specifically, the places most exposed to ground moisture, the AlorAir Sentinel HDi90 WiFi pulls 198 pints a day, covers up to 2,600 sq. ft., and runs on app-based monitoring with a built-in condensate pump.
Frequently Asked Questions
What is the most humid state in the United States?
Depends on the metric. Louisiana ranks first on combined morning-and-afternoon RH, Alaska can rank first on annual average RH, and Hawaii or Florida often top the list on dew point, the number that best tracks how muggy the air actually feels.
What is the least humid state in the United States?
Arizona usually takes the title by relative humidity, with Nevada and New Mexico right behind.
Is Florida or Louisiana more humid?
Depends on the metric and season. Louisiana ranks higher under some RH calculations, while Florida typically posts higher dew points and stickier conditions through summer.
Why is Alaska considered one of the most humid states?
Cold air needs very little water vapor to hit saturation, so Alaska's air sits close to that point most of the year. That produces a high RH reading even though the state's actual moisture content and its dew point stay low.
Is humidity higher in the morning or afternoon?
Morning, generally. Overnight cooling pushes air close to saturation, and afternoon heat lets air hold more moisture without saturating.
Which states have the lowest relative humidity?
Arizona, Nevada, and New Mexico rank lowest, with Colorado, Utah, and Wyoming close behind.
Final Takeaway
Three things to remember:
- Typically, Louisiana ranks as the most humid state on combined RH, and Arizona typically ranks as the least humid, a pattern that holds across most NOAA-based calculations.
- Alaska can rank highest of all 50 states on average RH without ever feeling as muggy as Florida or Louisiana, because cold air hits saturation with far less actual moisture in it.
- Dew point is usually the better number for how humid a state actually feels, rather than how close its air sits to saturation.
Before trusting any "most humid state" list, this one included, check the metric, the data source, and the time period. A ranking built on annual average RH, one built on dew point, and one built on afternoon-only readings can each hand you a different answer from the same weather data.
Stop Guessing, Measure Your Own Air!
State averages are a starting point, not a diagnosis. Your house has its own leaks, its own drainage, its own crawl space; the only way to know where you actually stand is to check it. Grab a hygrometer, watch it for a week, and if the number won't budge below 50%, The Dryair has a whole range of dehumidifiers built to bring a whole house back into range, no matter what the state ranking says.
