A sea breeze forms when the heavier, colder air over water moves inland while the lighter, warmer inland air rises, creating a breeze. The primary cause of sea breezes is temperature irregularities between land and ocean, because the land heats up faster than water.
According to USA Today, land and water heat up at different rates because water has greater heat capacity. As land rapidly heats up, the air above it grows warmer, and this warmer, less dense air rises, creating a pressure front. Meanwhile, the ocean heats up more slowly and the air is cool and dense with moisture. Because the warm air over land is rising, the cool air from the sea rushes in to fill the gaps. This process creates wind.
According to the University of Illinois, sea breezes occur during early afternoons because the sun has had time to heat up the land and the water. Sea breezes also occur during spring and early summer when water is still holding the cool temperatures of winter.
Often, sea breezes are accompanied with clouds because, as the moist cool air moves inland, it warms up and condenses into clouds. These clouds are known as the sea breeze front.