Most Humid States 2021

Humidity is the concentration of water vapor present in the air. Humid air is moist. Humidity is the most variable characteristic of the atmosphere and is a major factor in weather and climate.

Water vapor is the gaseous state of water and is typically invisible to the human eye. Atmospheric water vapor plays an important role in the weather and climate. It regulates air temperate by absorbing thermal radiation from the Sun and Earth and helps generate precipitation.

In weather reports, humidity is expressed as a percentage of the maximum amount of water vapor the air can hold at the same temperature, also known as relative humidity. Temperature determines the humidity capacity of air. As temperatures decrease, a volume of air can hold less water vapor.

When the air has a high moisture content (is humid), sweat cannot evaporate, leaving our bodies feeling sticky and hot. Our bodies must work even harder to cool off, resulting in excessive sweating, increased heart rate, increased respiration, and increase rate and depth of blood circulation. Overall, humidity can make the air temperature feel hotter than it is. In states with very hot summers and high humidity, being outside can feel like a burden.

Most Humid States in the U.S.

Because humidity is the concentration of water vapor in the air and water vapor comes from the evaporation of water from Earth’s surface, the states with the most humidity have a large presence of water.

Given this, landlocked states with very few large bodies of water tend to be the least humid. States like Nevada, Arizona, Colorado, and New Mexico have relatively low humidity and arid climates.

It’s easy to think that the most humid state in the U.S. is Florida or Louisiana since these states are relatively warm and near large bodies of water. The most humid state, however, is Alaska. This is is because, with relative humidity, humidity is expressed as a percentage of the maximum amount of water that air can hold at a given temperature. As temperatures decrease, the air holds less water vapor. Because of this, relative humidity can be much higher in cold areas even though there is less overall moisture in the air. This indicates one of the limitations of relative humidity.

Given this, the most humid states in the United States are a mix of warm, southern states and cold, northern states.

The ten states with the highest relative humidities are:

  • Alaska - 77.1%
  • Florida - 74.5%
  • Louisiana - 74.0%
  • Mississippi - 73.6%
  • Hawaii - 73.3%
  • Iowa - 72.4%
  • Michigan - 72.1%
  • Indiana - 72.0%
  • Vermont - 71.7%
  • Maine - 71.7%

Additionally, some of the most humid major cities in the U.S. are:

  • New Orleans, LA - 75.9%
  • Jacksonville, FL - 75.8%
  • Houston, TX - 74.7%
  • Orlando, FL - 74.1%
  • Tampa, FL.- 74.1%
  • San Francisco, CA - 73.7%
  • Seattle, WA - 73.3%
  • Miami, FL.- 73.2%
  • Portland, OR - 73.2%
  • Rochester, NY - 72.6%

Most Humid States 2021