More energy is required to heat the ocean than is required to heat the air or land, which means the ocean is very slow to respond to changes in the season.
The ocean’s temperature may be very different than that of the air above it. When the ocean is colder than the air above it, it cools the air above it. This creates a high pressure air mass. When the ocean is warmer than the air above it, it heats the air above it. This creates a low pressure air mass. Because air moves from high pressure to low pressure, winds are diverted toward that air mass. These diverted winds may generate or redirect storms.
The ocean heating air masses above it helps redistribute heat around the world along the path of ocean currents. For instance, the Gulf Stream carries warm water from the Gulf of Mexico along the east coast of the United States over to western Europe on a current known as the Gulf Stream. As a result, the east coast of the United States is hotter in the summer than the west coast, and west Europe is warmer than it would otherwise be. The California Current carries cool water from the poles along the west coast of the United States. As a result, California experiences cooler summers than the east coast and moderate winters.
In this way, the oceans help compensate for the uneven heating of the Sun. Without the ocean, the tropics would be a lot hotter than they are and the poles would be a lot colder. This is why the temperature at the surface of the ocean is so important.