A coastal low is a type of low-pressure system that develops along or near a coastline, usually along the eastern seaboard of the U.S. These systems often form when cold, dry air inland interacts with warmer, moist air over the ocean. The result can lead to the development of rain, wind, and sometimes snow, depending on the season. Coastal lows are especially common in the fall, winter, and early spring, when temperature contrasts between land and sea are strongest.

While coastal lows can produce significant weather impacts, they differ fundamentally from tropical systems like hurricanes or tropical storms. Tropical systems draw their energy primarily from warm ocean waters, which fuel intense thunderstorms and allow them to maintain a well-defined, symmetrical structure. In contrast, coastal lows develop from the contrast between warm and cold air masses rather than from ocean heat. This makes them more irregular in shape and often accompanied by fronts, like cold fronts or warm fronts, which help organize their precipitation patterns.

However, coastal lows can sometimes evolve into powerful storms, producing heavy rain, strong winds, coastal flooding, or even blizzard conditions in the colder months. Their winds are usually less uniform and less intense than hurricane-force winds. Still, for coastal communities, these storms can disrupt travel, cause flooding, and create hazardous conditions.

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Jennifer Gray is a weather and climate writer for weather.com. She has been covering some of the world's biggest weather and climate stories for the last two decades.