Cloud and Wind Effects 2 MET
If the cloud coverage is extensive, this will act like a "blanket", absorbing and re-radiating terrestrial radiation back to where it came from. As such, the temperature will not drop that much (though it will never increase, as the sun is not up!) If the sky is clear or there are few clouds, terrestrial radiation will escape into space and there will be a significant cooling overnight. In winter this can result in frost or fog.