How a sea breeze can make or break a day at the beach
The weather on the coast is often very different from that of a landlocked location, and a sea breeze can make or break a day at the beach.
People often flock to the beach for more than just a change in scenery. Many come to expect a sunny sky and comfortable conditions. Often, the weather fits this mold, but there are some exceptions.
The sun is the main engine of a sea breeze.
The sun heats the land at a much faster rate than the water. When the land heats up, the air over it begins to rise. Since the water is cooler than the land, the air over it begins to sink.
The rising air over the land and sinking air over the ocean then create a circulation. This circulation then creates a rush of cool air from the ocean that can extend beyond the beach to several miles inland.

In extreme cases, when the water is much colder than the land, a sea breeze can cause temperatures to dip by 10 to 30 degrees Fahrenheit. A comfortable day on the beach with temperatures near 80 can turn much cooler with a quick drop into the 60s and even the 50s.
Sometimes, a bank of low clouds and fog may also roll in from the ocean, which can further ruin a day on the beach.
The most likely time for much colder or cloudy conditions at the beach is during the spring and early summer.
However, most of the time during the middle and latter part of the summer, a sea breeze is much less potent but more on the weak end of the spectrum. High temperatures in the 90s from back home may be controlled by the sea breeze near the coast, where midday and afternoon temperatures hover in the middle 70s to the middle 80s.

The tide comes in as a woman seated in a beach chair dips her toes in the rising ocean waters, Wednesday, July 19, 2017, at Long Beach, New York. Temperatures in the 90's drew hundreds to the beach where a sea breeze cooled them off. (AP Photo/Kathy Willens)
At night, the land cools and the temperature difference between the water and land diminishes. As a result, the sea breeze circulation stops and may even be replaced by a breeze from the land. This is why there is often little temperature difference at the beach from day to night during the late spring and much of the summer.
A persistent light to moderate sea breeze can also push warm sea surface water toward the surf zone, much to the delight of bathers.
In addition to greatly mitigating temperatures at the beach, a sea breeze can offer a measure of protection from thunderstorms that erupt across the interior.

This satellite photo shows the effect a cool sea breeze has along the coast of Alabama and the Florida Panhandle. The area along the immediate upper Gulf of Mexico coast is clear, while puffy cumulus clouds riddle the interior South like popcorn. (NASA/Aqua satellite)
The light breeze from the ocean often creates a thick enough layer of cool, stable air to keep clouds and thunderstorms from reaching the immediate coastline in many cases. The sky may appear to be threatening with towering clouds much of the time across the mainland, yet the storms fail to encroach on the beach.
Similarly bays and large lakes, such as the Great Lakes, can create enough of a cooling cycle to keep shoreline areas cool and free of clouds and storms during the day.

This satellite image shows the effect of a cool breeze surrounding Lake Erie at 6:45 p.m. EDT, July 9, 2011. (NASA/Aqua satellite)
During the evening, as the sea breeze dies, there is a better chance for lingering thunderstorms to make the trip to the beach. However, many times the storms will also diminish before reaching the immediate coast. This is why, there tends to be less rain at the beach than across the mainland during the late spring and summer.
On days where the sea breeze is very light or parallel to the coast, practically no cooling may occur at the beach. Days such as this can be sweltering in a hot and humid weather pattern. Insects from the back bays may be a nuisance, and any showers over the interior may wander toward the beach or develop on the coast with little notice.
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