What Sets Off Bomb Cyclones

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OhOver the weekend, a bomb cyclone is expected to hit the southeastern United States. The forecast follows a week of bitter cold across most of the country and record snowfall in some areas, including New York and Dayton, Ohio.

Bomb cyclones – officially called bombogenesis – rapidly strengthen storms brewing in mid-latitudes. They are triggered when a storm’s central pressure drops a certain number of millibars in 24 hours, depending on location. They can form when cold air masses collide with warm air masses; for example, in the Northeast, they often occur when cold air from Canada flows into the warmer Gulf Stream.

Bomb cyclones can trigger intense winds that blow more than 80 miles per hour and heavy rain or snow. They typically form between October and March due to dramatic temperature contrasts during the colder months. Many Northeast cyclones are bombard cyclones, and these tend to appear in the latitudes between Georgia and New Jersey before reaching their peak around New England and parts of Canada.

“If you’re watching TV at night and the weather report comes on and you hear ‘bomb cyclone,’ that usually means there’s pretty active weather,” Andrew Orrison, a meteorologist with the National Weather Service in College Park, Maryland, told the Associated Press.

Read more: “The big collisions that are making the Snownadoes and the Arctic Sea smoke”

Bomb cyclones are not very common: They made up about 7% of all non-tropical low pressure systems near North America between 1979 and 2019, or an average of about 18 per year during that period. They are most common along the East Coast.

One of the deadliest Northeast storms arrived in March 1993, known as the Storm of the Century. It rushed from the Gulf of Mexico to Canada and killed more than 250 people in its wake. The storm began as a low pressure system and intensified as it moved north. This brought all kinds of bad weather, including winds of up to 140 mph, blizzards, and even tornadoes in some areas. All major airports and highways along the coast were closed at some point during the nor’easter, and millions lost power.

As with other weather phenomena, scientists believe climate change is intensifying in the Northeast – this is likely due to rising ocean temperatures and the ability of the warming atmosphere to hold more moisture. The researchers found that precipitation rates in the Northeast increased between 1940 and 2025, and they also noticed an upward trend in the maximum wind speed of the strongest of these storms, so part of the country can likely expect wilder winter conditions in the years to come.

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Main image: brian.gratwicke / Wikimedia Commons

• Molly Glick

  Published on January 29, 2026

  Molly Glick is the newsletter editor of Nautilus.