What is dew point?

Dew on grass in the early morning.

If you ever check current weather conditions, there's a good chance you have seen a mention of the dew point. The dew point is a value that is presented in degrees, but what does it tell us?

The dew point is simply the temperature the air needs to be cooled to achieve 100 percent relative humidity. When the air reaches 100 percent relative humidity, it cannot hold more water in the gas form.

The higher the dew point is, the more moisture in the air.

The dew point might sound like the relative humidity, but there are differences. The relative humidity is presented as a percentage while the dew point is presented in degrees. The relative humidity is relative to temperature. There could be 100 percent relative humidity with a temperature of 30 degrees or zero degrees.

Since the dew point is a measure of how much the air is saturated, the dew point can never be higher than the current air temperature. Air can not be more than 100 percent saturated with water.