I am sure you have seen the dew point graphic show up in our weather forecasts quite often. Some of you have even asked us why we use this graphic. Well wait no longer, because on this episode of Weather Word of the Week focuses on the dew point.

Why Use the Dew Point vs. the Relative Humidity?

By definition, the dew point is the temperature that the air must cool to in order for dew to form. It is a much better measure of the actual moisture. The relative humidity is an unreliable measurement of moisture, because it is relative to the air temperature. The relative humidity tells you how close, in percentage, that the air is to full capacity or saturation.

Think of it this way. Each value of air temperature holds a certain amount of moisture before it “fills up” and reaches its maximum capacity. The higher the temperature, the more moisture the air can hold.

Dew Point vs. Relative Humidity

To reach saturation you can do one of two things. You can add more moisture to the air or you can shrink the “container size” by lowering the air temperature. Both of these techniques will cause the atmosphere to reach saturation. Once it “fills up” the air will start to squeeze or condense the moisture out by creating water droplets.

How Does the Dew Point Affect You?

Well now you know that it is better to use dew point over the relative humidity, but how does this measure of moisture affect you?

The higher the dew point is the more humid the air feels outside. Here is a break down of the different “categories” of comfort.

Tropical71° to 75°
Sticky66° to 70°F
Humid61° to 65°F
Comfortable55° to 60°
Dew Point Levels with Descriptive Term

The more moisture that is in the atmosphere, the more difficult your sweat will evaporate. It stays clinging to your skin causing you to feel hotter by trapping your body heat inside. With more water vapor in the air, there is less oxygen per volume which makes it harder to breathe when exercising. Always make sure to slow down and take breaks if needed.

That’s it for this episode of Weather Word of the Week. If you want to catch previous episodes, you can view them HERE!