During the night, inland air cools faster than the air near the coast or above the water bodies (in our case the Mediterranean Sea). Due to this temperature difference, the colder air moves offshore driven by drainage wind following the river valleys, streams and down slope the mountain ranges. A coastal front is formed when the colder air mass interacts with the warm and moist maritime air mass. This interaction enhances the vertical movement of the warm air mass that cools and may condensate forming clouds and in some cases producing precipitation. This nocturnal coastal front formation has been analyzed and quantified by using observations and the results of the numerical experiments performed with the WRF-ARW mesoscale model. The role of, for instance, the shape of the coast and the sea surface temperature, is investigated.