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Measuring Dew Point and Heat Index

PocketLab Voyager, Weather, and Air can all measure dew point and heat index. Learn about them both here.

What is Dew Point?

Dew point indicates the temperature to which the air would need to cool to be 100% saturated with water vapor (relative humidity of 100%). Dew point is calculated from the current air temperature and the relative humidity of the air. The dew point can never be higher than the current air temperature because air can never be more than 100% saturated with water. If the dew point and the air temperature are the same, the air can no longer hold water vapor and condensation occurs.

Dew point is often used as an indication of how “comfortable” the weather is when considering both temperature and humidity. A dew point of 70°F (21.11°C) would be considered uncomfortable because if the air temperature is 80°F(26.67°C), for example, it would be extremely humid while being fairly hot. If the air temperature is much higher, 100°F(37.78°C) for example, it would be extremely hot while still being fairly humid. Also, the more saturated the air the more difficult it is for sweat to evaporate which is how the body cools itself on a hot day. Generally, dew points of 50°F - 59°F are considered comfortable, 60°F - 69°F are considered uncomfortable, and 70°F and up are considered very uncomfortable.

What is Heat Index?

Heat index indicates how hot it “feels” when considering both air temperature and relative humidity. For example, at 92°F and 40% humidity the heat index is 94°F, but at 70% humidity it jumps up to 112°F.