How Does a Sea Breeze Form?

Walking outside during the summer can feel like walking into the bathroom after someone takes a shower. The muggy air gives you a great big unwanted hug, fogging up your glasses and forcing you into a gross and near-immediate sweat. If you're seeking relief, head to the beach: One of the great benefits of being near the coast is the cool afternoon breeze that takes the edge off of a hot summer day.

The sea breeze is a wind circulation that forms near the coast when there's a large difference between the temperature of the air over land and the temperature of the air over water. Land heats up much faster than water, so there's usually a big temperature gradient between, say, Mobile, Alabama, and the Gulf of Mexico just a few miles offshore.

The sea breeze process starts when warm, unstable air over the land begins to rise. This rising air creates a small area of lower air pressure at the surface. As part of Mother Nature's balancing act, cooler air over the ocean starts to rush toward land to fill the void left by the rising air. This eventually creates a circulation that continues for as long as daytime heating is present. As cooler air lingering over the water starts to spill inland, humidity goes up a bit, but air temperatures drop as much as 10°F to 15°F once it passes through. You don't need to be on the beach to reap the benefits of this phenomenon, either: A sea breeze can travel as much as 50 miles inland in some locations.

Aside from their cooling relief, sea breezes are most notable for the thunderstorms they can trigger near the coast. Sea breeze thunderstorms don't last for very long, but they can be a doozy, sometimes producing flooding rains, vivid lightning, and occasionally some damaging wind gusts.

Central Florida is famous for dealing with sea breeze thunderstorms almost every day during the warm season. The state's narrow shape allows two sea breezes—one from the Gulf of Mexico and one from the Atlantic Ocean—to collide with each other right in the middle of the peninsula. One sea breeze usually packs enough punch to fire up a hefty storm, but the lift created by two sea breezes colliding can trigger especially vivacious storms, as anyone who's ever visited Orlando's theme parks can tell you.

Once the Sun goes down and the sea breeze wanes, the opposite effect begins to take hold. Water holds onto its heat much better than the land, and as a result the air over the water usually stays warmer at night than the air over land. This disparity between land and sea causes what's known as a land breeze; it's the exact process that goes into a sea breeze, but blowing from the land out toward the sea instead. This process can also lead to thunderstorms, just close enough to the coast that anyone standing on the beach in the early hours of the morning can watch lightning flashing off in the distance.