The Most Humid Cities in America
Rank America’s cities by relative humidity and a surprise shows up near the top: the cool, drizzly Pacific Northwest, tied with the Gulf Coast. That’s because relative humidity isn’t what makes air feel muggy — dew point is. Here are both numbers, ranked from NOAA data, with the catch explained.
By NOAA’s average morning relative humidity, the most humid cities in America cluster on the upper Gulf Coast — Port Arthur, Texas and Lake Charles, Louisiana lead at 90%, with Brownsville (90%), Baton Rouge (89%), Jacksonville and Tallahassee (88%) close behind. But right in the middle of that group sits Quillayute, Washington, at 89% — a cool, fog-bound stretch of Olympic Peninsula coast that no one would call muggy.
That contradiction is the whole story. Relative humidity is a share, not an amount, so it runs high anywhere the air is cool — which is why the Pacific Northwest keeps turning up on “most humid” lists it has no business being on. What actually feels muggy is dew point, the real quantity of water in the air, and by that measure the muggiest US cities are unambiguously on the Gulf Coast. Below are both rankings and why they disagree.
America’s Most Humid Cities, by NOAA Relative Humidity
Ranked by annual morning relative humidity (near the daily peak), from NOAA’s Comparative Climatic Data, with the afternoon reading alongside. Gulf Coast cities are shaded; the two cool-climate intruders — Quillayute and San Francisco — are flagged, because they’re the clearest proof that a high humidity percentage doesn’t mean muggy air.
| # | City | Morning RH | Afternoon RH |
|---|---|---|---|
| 1 | Port Arthur, TXUpper Texas coast | 90% | 63% |
| 2 | Lake Charles, LAUpper Gulf coast — among the highest US dew points | 90% | 62% |
| 3 | Brownsville, TX | 90% | 60% |
| 4 | Quillayute, WACool and drizzly — not muggy | 89% | 74% |
| 5 | Baton Rouge, LA | 89% | 59% |
| 6 | Jacksonville, FL | 88% | 56% |
| 7 | Tallahassee, FL | 88% | 54% |
| 8 | New Orleans, LA | 87% | 62% |
| 9 | Mobile, AL | 87% | 57% |
| 10 | San Francisco, CAMarine fog, not muggy heat | 87% | 69% |
| 11 | Astoria, OROregon coast — cool | 86% | 74% |
| 12 | Tampa, FL | 86% | 58% |
| 13 | Houston, TX | 85% | 59% |
| 14 | Galveston, TX | 85% | 69% |
| 15 | Pensacola, FL | 85% | 60% |
Annual average relative humidity, NOAA NCEI Comparative Climatic Data, “Average Relative Humidity — Morning (M), Afternoon (A)” table, pulled October 10, 2026. Morning readings are the time-zone-adjusted early-day observation (roughly 4–8 a.m. local, near the daily RH maximum); afternoon is roughly noon–2 p.m. (near the minimum). For contrast, the driest major cities are Las Vegas (36% morning / 20% afternoon) and Phoenix (46% / 23%).
The giveaway: who tops afternoon humidity
Rank by afternoon relative humidity instead — the daytime hours people are actually outside — and the Gulf Coast drops off the top entirely. The leaders are cool, marine places where the air never warms enough to dry out:
Quillayute, Astoria and Juneau — none of them warm — hold afternoon humidity near 74%, higher than Houston (59%) or New Orleans (62%). If afternoon relative humidity were the muggiest-city test, the answer would be the Oregon coast. It plainly isn’t, which is the tell that relative humidity is the wrong tool.
Why Dew Point Beats Relative Humidity for “Muggy”
Relative humidity answers a trick question: not “how much water is in the air” but “how close is the air to full, at this temperature?” Because warm air can hold far more moisture than cold air, the same lungful of air can read 90% relative humidity at dawn and 55% by mid-afternoon without a single molecule of water changing. That’s why morning RH is high almost everywhere, and why cool climates post high RH all day.
Dew point fixes this. It’s the temperature the air would have to cool to for its moisture to saturate — a direct measure of how much water is actually present, independent of the current temperature. The National Weather Service’s own advice is blunt: for comfort, “look at the dew point instead of the RH.” Its example makes the point — air at 80°F with a 60°F dew point is only 50% relative humidity but feels muggy, while 30°F air at 100% relative humidity feels nothing of the sort.
- ≤ 55°F — dry and comfortable
- 55–65°F — getting “sticky”, muggy evenings
- ≥ 65°F — a lot of moisture in the air, becoming oppressive
Gulf Coast summer dew points routinely sit in the low-to-mid 70s°F — well into the oppressive band — which is why Lake Charles, New Orleans, Houston, Mobile and Jacksonville feel the way they do in July. The Pacific Northwest, despite its sky-high relative humidity, almost never gets there: its air is too cool to carry that much water. That one number is the difference between fresh and suffocating, and it’s why we built the methodology behind these numbers out in how weather records are actually verified.
The Geography of Muggy Air
High dew points need two things: a nearby source of warm water and a wind pattern that pumps its moisture onshore. The US has one place that does this better than anywhere else.
- The Gulf of Mexico is a moisture factory. Bathwater-warm for half the year, it feeds a steady stream of high-dew-point air into Texas, Louisiana, Mississippi, Alabama and Florida. The summertime Bermuda High parks over the western Atlantic and its clockwise flow pushes that Gulf air inland for weeks at a time — the reason the upper Texas/Louisiana coast (Port Arthur, Lake Charles, Galveston) is the muggiest corner of the country.
- Florida gets it from two seas at once. Flanked by the Gulf and the Atlantic and sitting at subtropical latitude, Jacksonville, Tampa, Pensacola and Miami live under high dew points from June into October, which is also why afternoon sea-breeze thunderstorms are a near-daily summer ritual.
- The Pacific Northwest is humid but cold. Onshore flow off a cool ocean keeps Quillayute, Astoria and the Washington–Oregon coast saturated — high relative humidity, persistent low cloud — but the water temperature caps the dew point in the 50s, so the air reads humid and feels fresh. Same statistic, opposite experience.
So What’s the Honest Answer?
If someone asks for the most humid city in America, the correct reply is a question: by which number? By average relative humidity it’s a tie between the Gulf Coast and the cool Northwest coast, both near 90% in the morning. By how the air actually feels — by dew point — it’s the Gulf Coast, and the upper Texas–Louisiana coast most of all. Any list that hands you a single “muggiest city” without saying which metric it used is skipping the only part that matters. If you want to see how the moisture translates into actual rainfall, that’s a different ranking — the rainiest cities in America — and a famously humid place like Seattle doesn’t crack it. Look up how muggy your own town runs on any past date with our weather-history tool, and tell us whether the number matches how your summer actually feels.
Frequently Asked Questions
What is the most humid city in the US?
It depends on the number you use. By NOAA’s average morning relative humidity, the upper Texas and Louisiana coast ties the top — Port Arthur and Lake Charles at 90%, Brownsville at 90%, Baton Rouge at 89% — alongside the cool, foggy Pacific Northwest coast (Quillayute, Washington, at 89%). By how muggy the air actually feels, which tracks dew point rather than relative humidity, the muggiest US cities are on the Gulf Coast: Lake Charles, New Orleans, Houston, Mobile and Jacksonville, where summer dew points routinely climb into the oppressive 70s°F.
Is relative humidity the same as how humid it feels?
No. Relative humidity is the share of the moisture the air could hold at its current temperature, so it rises overnight as the air cools and falls in the afternoon heat even when nothing changes. Dew point measures the actual amount of moisture in the air. The National Weather Service advises looking at the dew point for comfort: 80°F air with a 60°F dew point is only 50% relative humidity but feels muggy, while 30°F air at 100% relative humidity feels nothing of the sort.
Why does the Gulf Coast feel so much muggier than Seattle?
Because dew point, not relative humidity, is what you feel — and the Gulf Coast has far higher dew points. The Pacific Northwest coast actually posts higher afternoon relative humidity (Quillayute and Astoria near 74%) than Houston or New Orleans, but it is cool, so the air holds little moisture and feels fresh. The Gulf Coast pairs high moisture with heat: summer dew points above 70°F, which the NWS calls oppressive. Same high humidity reading, completely different air.
Keep Exploring
This is the humidity chapter of our US city-climate series. See which cities get the most wind in the windiest cities in America, the most and least sun in the sunniest and cloudiest cities, and the most rain in the rainiest cities in America. Humidity is also why heat waves on the Gulf feel deadlier than the same temperature out West — see the worst heat waves in US history. Browse the rest at our weather records.
Sources & Method
Relative humidity figures are the annual morning and afternoon averages from NOAA’s Comparative Climatic Data (National Centers for Environmental Information), “Average Relative Humidity — Morning (M), Afternoon (A),” pulled and ranked on October 10, 2026. The dew-point comfort scale and the dew-point-vs-relative-humidity distinction are from the National Weather Service’s “Dew Point vs. Humidity” guide. The ranking is limited to US cities with a long NOAA record; Alaska and Hawaii stations appear only as reference points. Gulf Coast summer dew points regularly exceeding 70°F reflect the NWS oppressive threshold applied to the region’s well-documented warm, moisture-laden summer air; precise station dew-point climatology varies year to year.