Dew Point Temperature

Dew point is a measure of atmospheric moisture. It is the temperature to which air must be cooled to reach saturation (assuming air pressure and moisture content are constant). A higher dew point indicates more moisture present in the air. It is sometimes referred to as dew point temperature, and sometimes written as one word (dewpoint). Frost point is the dew point when temperatures are below freezing.

In simpler terms: the dew point, or frost point, is the temperature at which dew or frost will form should the air temperature fall sufficiently. Other things being equal, as the temperature falls, the relative humidity rises, reaching 100% at the dew point, at least at ground level. Dew point temperature is never greater than the air temperature, since the relative humidity cannot exceed 100%.