A sea breeze is a mesoscale circulation produced by heating differences between the land and water. The direction of wind flow at the surface in a sea breeze is from the sea and into the land. A sea breeze will keep temperatures moderated along and near the coast. The strength of the sea breeze will depend on several factors with the most important being the temperature gradient. The sea breeze may not set up at all if the synoptic weather pattern overpowers the mesoscale environment such as the case of a passage of a front. When the synoptic environment is fairly benign the strength of the sea breeze is going to primarily depend on the temperature difference between the ocean and land. The strength of the sea breeze tends to be strongest from the late morning to the late afternoon since at this time the difference in temperature between the land and ocean is at the greatest. Suppose the land temperature is 90 F and the water temperature is 75 F. Since the temperature is warmer over the land this air will be less dense and more inclined to rise. The air over the ocean will flow toward the land to replace the rising air. This sets up a circulation that actually begins aloft due to the density and buoyancy differences of the air over the ocean and land.

The land breeze develops at night when the temperature pattern between the ocean and land are reversed. In a land breeze the land will be cooler than the ocean. Suppose the land temperature is 70 F and the ocean temperature is 75 F. In this case the air over the ocean is warmer and thus the circulation will reverse to a flow from the land toward the sea at the surface. A land breeze will often be weaker than a sea breeze since the temperature difference between the land and water is not as great. In some cases the land does not cool off to being significantly less than the ocean temperature which results in a slacking of the sea breeze but no well defined land breeze setting up at night. Along with synoptic conditions, it is important to know the water temperature and the expected high and low over the land. This will help the forecaster determine how established the sea breeze and land breeze will be that day.