Under what conditions would dew not form?

MIKE MOSS SAYS:      Edili,     Dew requires a surface that is colder than the dew point of the air in contact with it, so dew will not form when the surface is warmer than the ambient dew point. In nature, this can occur due to very dry air that has a correspondingly low dew point (in which case surface objects may become very cold, but no dew form because there simply isn't enough water vapor present to become saturated), or it can occur because winds or cloud cover prevent radiational cooling at night from lowering the temperature of objects at the surface (car tops, grass, mailboxes, etc) sufficiently to match the dew point.