Some of America’s largest cities experience consistently high humidity throughout the year. Among the major U.S. cities included in these rankings, the most humid have annual average relative humidity levels above 72.5 percent.
New Orleans, Louisiana, ranks first, with an annual average relative humidity of 75.9 percent. Jacksonville, Florida, is a close second at 75.8 percent, followed by Houston, Texas, at 74.7 percent.
The figures are annual averages based on humidity observations collected between 1961 and 1990.
The rankings cover 56 major U.S. cities representing the country’s largest urban areas, specifically those with more than one million residents in 2020.
Most Humid Major Cities in the U.S.
| Rank | City | Average Annual Relative Humidity |
|---|---|---|
| 1 | New Orleans, Louisiana | 75.9% |
| 2 | Jacksonville, Florida | 75.8% |
| 3 | Houston, Texas | 74.7% |
| 4 | Orlando, Florida | 74.1% |
| 5 | Tampa, Florida | 74.1% |
| 6 | San Francisco, California | 73.7% |
| 7 | Seattle, Washington | 73.3% |
| 8 | Miami, Florida | 73.2% |
| 9 | Portland, Oregon | 73.2% |
| 10 | Grand Rapids, Michigan | 72.7% |
| 11 | Rochester, New York | 72.6% |
Florida features prominently in the rankings, with Jacksonville, Orlando, Tampa and Miami all appearing among the cities with the highest annual average humidity.
When Is Humidity Highest During the Day?
Humidity changes throughout the day as temperatures rise and fall. Relative humidity usually reaches its highest level during the coolest part of the day because cooler air can hold less water vapor.
For these cities, the daily humidity peak generally occurs between 4 a.m. and 7 a.m. local standard time.
Houston records the highest average morning humidity among the cities listed, reaching 89.7 percent at around 6 a.m. Jacksonville and Orlando follow closely, with average morning humidity of 89.2 percent and 89.0 percent, respectively.
Cities With the Highest Morning Humidity
| Rank | City | Average Peak Humidity | Time |
|---|---|---|---|
| 1 | Houston, Texas | 89.7% | 6 a.m. |
| 2 | Jacksonville, Florida | 89.2% | 4 a.m. |
| 3 | Orlando, Florida | 89.0% | 4 a.m. |
| 4 | New Orleans, Louisiana | 87.6% | 6 a.m. |
| 5 | Tampa, Florida | 87.5% | 7 a.m. |
| 6 | Portland, Oregon | 84.8% | 4 a.m. |
| 7 | Raleigh, North Carolina | 84.6% | 7 a.m. |
| 8 | Nashville, Tennessee | 84.1% | 6 a.m. |
| 9 | Birmingham, Alabama | 84.1% | 6 a.m. |
| 10 | Miami, Florida | 83.9% | 7 a.m. |
The pattern is particularly noticeable in the Gulf Coast and Florida cities. Houston, Jacksonville and Orlando all average close to 90 percent humidity during their daily morning peak.
Humidity During the Afternoon
As temperatures rise during the day, relative humidity generally falls. Even so, many of the cities with high annual humidity remain relatively humid during the afternoon.
Among the cities in the source data, average daily minimum humidity remains above 58.5 percent. Milwaukee has the highest average minimum humidity, at 62.8 percent, usually occurring around noon.
Cities With the Highest Daily Minimum Humidity
| Rank | City | Average Lowest Daily Humidity | Time |
|---|---|---|---|
| 1 | Milwaukee, Wisconsin | 62.8% | Noon |
| 2 | Buffalo, New York | 62.4% | 1 p.m. |
| 3 | Grand Rapids, Michigan | 62.0% | 1 p.m. |
| 4 | Seattle, Washington | 61.7% | 4 p.m. |
| 5 | Rochester, New York | 61.0% | 1 p.m. |
| 6 | Cleveland, Ohio | 61.0% | 1 p.m. |
| 7 | New Orleans, Louisiana | 60.7% | Noon |
| 8 | Miami, Florida | 60.5% | 1 p.m. |
| 9 | San Francisco, California | 59.4% | 4 p.m. |
| 10 | Los Angeles, California | 58.7% | 4 p.m. |
| 11 | Portland, Oregon | 58.6% | 4 p.m. |
What the Humidity Rankings Show
The rankings illustrate that high humidity is not limited to one part of the United States. Southern cities dominate the annual averages, particularly in Louisiana, Florida and Texas, while several cities in the Pacific Northwest, Great Lakes region and Northeast also experience relatively high humidity.
There is also a clear difference between annual humidity and daily humidity patterns. New Orleans ranks highest for annual average relative humidity, while Houston records the highest average morning humidity in the morning rankings.
During the warmest part of the day, humidity generally falls. However, cities such as Milwaukee, Buffalo and Grand Rapids maintain relatively high minimum humidity levels compared with many other large U.S. cities.
How Humidity Changes During the Day
Relative humidity is closely linked to air temperature. When temperatures are lower, the air can hold less water vapor, so the relative humidity tends to be higher. As temperatures rise during the day, relative humidity generally decreases.
This explains why humidity readings are commonly highest in the early morning and lower during the afternoon.
However, humidity is only one measure of how humid a place feels. Temperature, wind, rainfall and other atmospheric conditions also affect people’s perception of how muggy or comfortable the weather is.
Data Source
The figures in these rankings are based on annual average humidity readings from 1961 to 1990.
Reference: World Data Center for Meteorology, Climate of the World.