Virginia summers getting more hot and humid

Published: Jul. 6, 2016 at 11:58 AM EDT
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If you step outside, you can feel just how sticky it is. It's often referred to as relative humidity, but the reason it's so humid is actually because of the dew point, or amount of moisture in the air. The higher the dew point, the more moisture in the air.

Warmer, summer temperatures can hold significant amounts of moisture, which is why it often feels so humid.

New research from Climate Central suggests summers are not just getting hotter, they’re getting more muggy as the dew point temperature is rising due to climate change.

This is especially noticeable across Virginia, where rising trend in the summer dew points have increased more than a degree since the 1980s.


As summers get hotter from the increase in greenhouse gases, they are also getting stickier. More evaporation occurs in a warming atmosphere, and on a world where water covers nearly three-quarters of the surface, it means an increase in water vapor in the air.

During hot summer days, additional moisture in the air stresses the body by making it harder to cool itself through perspiration. This effect is not just irritating and uncomfortable, it can also raise the risk of heatstroke and heat exhaustion and in some cases, death. According to the Centers for Disease Control, more than 7,800 people died from heat-related illnesses from 1999-2009.

More moisture in the air also keeps the nights warmer, as humid air does not cool as easily as dry air. The warmer and more sultry nights mean that the body has less time to recover after a hot and steamy day in the sun, which further increases the risk of heat-related illnesses.

As both temperature and dew point rise with climate change, the number of days in which they combine to raise the risk for heat-related illness is also expected to climb. The number of danger days — days when the heat index (the combination of heat and humidity) is at least 105°F — will likely increase substantially in much of the country.


While climate is the long-range analysis of patterns, and weather is the more short-term view, they can often go hand-in-hand.

For instance, with higher dew points and more moisture in the air, when a storm does develop, we might expect the rain to be more intense. Downpours will be more likely and when the rain falls in the same areas, perhaps an increase in flooding too.