Jun 23, 2023

Dew point is a better indicator of humidity versus relative humidity

Chief Meteorologist

Chief Meteorologist Alex Kirchner explains why the dew point is a great way to track humidity levels

Meteorologists talk plenty about the dew point temperature during the summer, as it is a great indicator of humidity and a condition to watch when severe weather is possible.

So what is it? The dew point temperature is the point when the air becomes completely saturated with moisture. This means the air can't hold onto any moisture, so it condenses out and helps form things like dew, fog, clouds and more.

The closer the air temperature is to the dew point, the more you "feel" the humid air. The higher the dew point, the more moisture there is in the air.

Why is it better than using relative humidity to talk about how humid the air is? The relative humidity is dependent on the air temperature, while the dew point isn't.

As the air warms up, the relative humidity goes down, but the moisture levels in the air haven't changed. If you look solely at the relative humidity, you'd think the air would be getting less humid, when in fact the humidity hasn't changed at all.

How can you tell how humid the air is based on the dew point? During the summer, dew points above 60 degrees mean the air is somewhat humid. You can start to feel the humidity in the air, especially above 65 degrees. When the dew point is in the 70s, the air feels muggy. By 80 degrees and above, it's "air you can wear", as in the air feels extremely humid and tropical. 80-degree dew points are pretty rare for the Midwest!

We need the air to be humid to help boost the potential for severe storms. The higher the dew point, the more explosive and unstable the atmosphere can get. Drier air is an enemy of severe storms, so tracking where the higher dew points are (or how they may change) helps meteorologists track and determine where severe storms may erupt.

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Chief Meteorologist