Weather Facts

What is a Sea Breeze?

Have you ever been on the beach and all of a sudden the wind shifts from off of the water and the temperature drops quite drastically? This sudden shift in wind which can be quite refreshing during spells of hot weather is most likely the result of a sea breeze. Sea breezes keep coastal areas cooler in the spring and summer on many, but not all days. What causes the sea breeze? It is really quite simple. Land heats up faster than the water. The air over the land begins to warm and since warm air is less dense than cool air, it rises as it is lighter than the cooler air above it. As the warm air rises over the land, the cooler air over the water begins to move in to replace the air that is rising over the land. This causes the wind at the surface to switch direction and blow from the water. As the afternoon wears on, the sea breeze normally strengthens and moves further and further inland. Its cooling relief can sometimes be felt many miles inland. Once the sun sets, the air over the land begins to cool and the air stops rising. The sea breeze stops blowing and many times reverses itself and becomes a land breeze as the night wears on. The land cools rapidly at night and the air begins to descend. If the normal gradient wind between the high and low pressure areas on the weather map is blowing from the land, it will resume at night. Even if there isnít much of a gradient wind, a light land breeze normally develops as the air moves out over the relatively warmer water. Some days, when the winds are blowing quite strong from off the land, a sea breeze will not develop. It takes certain conditions to produce a sea breeze. Note that sea breezes can enhance thunderstorm development as they produce a sea breeze front. This is where the cool, ocean air meets the opposing air flow as the sea breeze heads inland. This causes additional lift in the atmosphere, which can cause thunderstorm development. Sea breezes can raise humidity levels which can offset the cooling effect that they will bring to coastal communities. Most of the time, they are welcome relief to anyone living along the coast.