Humidity in the United States

Cities With Low Humidity in the USA

The desert cities of Las Vegas and Phoenix top the list of major American cities with the lowest humidity. Las Vegas clearly ranks as the driest, with an average relative humidity level of just 30 percent. Phoenix joins in as the only other big city that averages less than 40 percent humidity.

At the next step up in humidity levels sit Denver and Salt Lake City, both having well under 60 percent humidity on average year round.

The four cities consistently rank as the least humid in the United States, regardless of the time of day. The rest of the top ten least humid cities hang together in the range of 63 to 66 percent humidity.

These numbers are annual averages based on humidity readings taken every three hours from 1961 to 1990.

The major cities included in the weather rankings here represent the US urban areas with the most people, all those with over one million residents in 2010.

Average relative humidity (%) for the least humid US cities
City Humidity
Las Vegas, Nevada 30.3
Phoenix, Arizona 36.6
Denver, Colorado 52.0
Salt Lake City, Utah 55.3
New York, New York 63.0
Washington, DC 64.3
Oklahoma City, Oklahoma 64.9
Dallas, Texas 65.4
Baltimore, Maryland 65.8
Hartford, Connecticut 66.0

Lowest Morning Humidity

Ten of America's large cities stay under 78 percent humidity at their highest levels of the day, the early morning. Most major cities get above 70 % each day. But the least humid city, Las Vegas, averages less than 40 % humidity in the early morning.

The time of day when humidity levels are usually highest depends on the city and ranges from 4 am to 7 am local standard time.

Highest humidity (%) of the day, on average, for America's least humid cities
City Humidity Time
Las Vegas, Nevada 39.6 4 am
Phoenix, Arizona 51.0 5 am
Salt Lake City, Utah 67.1 5 am
Denver, Colorado 67.3 5 am
New York, New York 71.1 7 am
Boston, Massachusetts 74.7 4 am
Washington, DC 74.9 4 am
San Diego, California 76.1 4 am
Baltimore, Maryland 76.9 7 am
Philadelphia, Pennsylvania 77.9 4 am

Lowest Afternoon Humidity

As the humidity drops lower into the afternoon, the four least humid cities continue to top the list of cities with lowest humidity. Ten major US cities average a daily low of less than 51 percent humidity.

Some places are among the least humid cities in the afternoon, but not during the morning. The humidity at Sacramento, San Antonio and others declines enough during the day for them to join the afternoon ranks of least humid cities.

Humidity levels in these cities normally reach their lowest point for the day between 2 pm and 5 pm local standard time.

Lowest daily humidity (%), on average, for the least humid US cities
City Humidity Time
Las Vegas, Nevada 20.3 4 pm
Phoenix, Arizona 22.6 5 pm
Denver, Colorado 34.2 2 pm
Salt Lake City, Utah 40.8 2 pm
Sacramento, California 45.5 4 pm
San Antonio, Texas 48.1 3 pm
Oklahoma City, Oklahoma 48.1 3 pm
Dallas, Texas 48.5 3 pm
Austin, Texas 48.9 3 pm
Charlotte, North Carolina 50.7 4 pm
Reference

World Data Center for Meteorology. Climate of the World.

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AMERICAN WEATHER