Now frost is a covering of ice crystals on the surface produced by the depositing of water vapor to a surface cooler than 0Â° C (32Â° F). The deposition occurs when the temperature of the surface falls below the frost point.Similarly, dew forms when the air or surface temperature falls below the dew point temperature.herefore, frost is not frozen dew.). Thus, if the temperature on the ground or an object such as a bush or a car windshield near the ground falls below the frost point, frost crystals may form. But the measured  surface temperature  may still be above freezing.