Is there a relationship between dew point and impending nighttime low temperatures?
There is a direct relationship between dew point and nighttime low temperatures. The dew point is the temperature to which air would have to be cooled to become saturated that is, for its relative humidity to become 100%. High dew points indicate high water vapor content high humidity; low dew points indicate low water vapor content. High amounts of water vapor in the air slow nighttime cooling significantly because when vapor condenses into liquid to form fog and dew it releases latent heat. The latent heat released by condensation keeps the temperature from dropping as low as it would when no condensation takes place. In the summer, especially, more typically humid locations especially locations east of the Rockies tend to have relatively high dew points. When the dew point is close to the air temperature, there is a lot of water vapor in the air (leading to muggy conditions), and this keeps the temperatures from dropping significantly overnight. In fact, when you see that the averag
