A sea breeze or onshore breeze is any wind that blows from a large body of water toward or onto a landmass; it develops due to differences in air pressure created by the differing heat capacities of water and dry land. As such, sea breezes are more localised than prevailing winds. Because land heats up much faster than water under solar radiation, a sea breeze is a common occurrence along coasts after sunrise. By contrast, a land breeze or offshore breeze is the reverse effect: dry land also cools more quickly than water and, after sunset, a sea breeze dissipates and the wind instead flows from the land towards the sea. Sea breezes and land breezes are both important factors in coastal regions' prevailing winds. The term offshore wind may refer to any wind over open water.

Wind farms are often situated near a coast to take advantage of the normal daily fluctuations of wind speed resulting from sea or land breezes. While many onshore wind farms and offshore wind farms do not rely on these winds, a nearshore wind farm is a type of offshore wind farm located on shallow coastal waters to take advantage of both sea and land breezes. (For practical reasons, other offshore wind farms are situated further out to sea and rely on prevailing winds rather than sea breezes.)