During the day the wind at the coast blows from ocean to land. At night it's opposite way around. The reason: During the day the ground is warmed faster and more than the water. The warm air above the ground ascends and draws in the air from the ocean, so the wind blows from the ocean to the land. At night, the air over the ground cools faster than over the water. Now the wind blows vom ground to the ocean. This phenomena occurs also at the coasts of greater lakes like Lake Constance.