The Bermuda High: A Recipe For Heat, Humidity | WeatherBug
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The Bermuda High: A Recipe For Heat, Humidity

July 7, 2023
By WeatherBug Meteorologist, Alyssa Robinette
Known as the “Heat Pump,” the Bermuda High is a yearly occurrence that brings heat and humidity to the East Coast every summer. It can also affect the Atlantic hurricane season. 

The Bermuda High is a high pressure system that sets up over the Atlantic Ocean from late spring to early fall, but is most dominant during the summer. It is located southeast of the Mid-Atlantic coast near Bermuda but can strengthen and shift directions throughout this several month period. It is a key factor in determining the weather across the eastern U.S. and can also play a role in the Atlantic hurricane season.

This high pressure system has a clockwise circulation, which puts the eastern U.S. in the position to receive south to southeast winds. These winds pump in heat and humid air from the Atlantic Ocean and Gulf of Mexico into the East. It can often lead to many days or even weeks of hot and sticky weather, especially across the Southeast.

Not only does it heat up summertime temperatures in the East, but the Bermuda High can also impact the frequency, intensity and direction of tropical storms and hurricanes. Air within this high pressure system has a sinking motion, which causes the air to become drier and warmer. This warmer, drier air can suppress cloud formation off the water allowing the sun to be more able to directly heat the ocean surface. With more sunlight, water temperatures increase and can be major breeding grounds for strengthening and aiding the formation of hurricanes.

Due to the clockwise direction of flow, waves of low pressure that develop off the coast of West Africa are directed towards North America and the Caribbean. This can also help in the formation of tropical activity. The exact location of the high pressure system can influence the direction tropical storms and hurricanes will go.

If the high pressure remains to close to the Atlantic Coast, it tends to push tropical activity into the Caribbean Sea and the Gulf of Mexico. If the high pressure shifts too far east, tropical activity may end up far enough east where disturbances stay over the sea. A normal Bermuda High often directs hurricanes to move along the East Coast and then eventually back out over open waters.

In general, when the Bermuda High is displaced more south and westward, it can stretch its western edges close to and even over the East Coast. If and when this set-up occurs, the eastern U.S. coastline can be extremely susceptible to hurricanes.

During the winter, the Bermuda High shrinks and moves to the south of the Azores, islands in the east-central Atlantic. This allows more variable weather to return to the East Coast just as autumn begins and the hurricane season nears its end.