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Nor'easters are powerful and often destructive cyclonic storms that primarily impact the East Coast of North America. Some of these weather events have been so fierce that they earned the names "Perfect Storm," "Storm of the Century," and "Snowmaggedon."

Historical records and climate models agree that these destructive storms are becoming less common as a consequence of a warming climate. Less frequent, however, does not mean less intense.

New research in the Proceedings of the National Academy of Sciences finds that though less frequent, the strongest nor'easters are becoming more intense, packing powerful winds and dropping greater amounts of precipitation. This is a worrying trend for storms that have caused billions of dollars of damage as well as injury and death.

This intensification trend was overlooked in previous studies, which focused more on averages rather than extremes. Also, other studies that suggested little or no changes in nor'easter intensity often failed to directly assess key factors such as wind speeds and precipitation trends.

To identify and track the evolution of nor'easters, the researchers applied a cyclone tracking technique to a dataset covering the years 1940 to 2025 to create a comprehensive storm record. From this, they defined what they categorized as "impactful nor'easters," those with a specific minimum sea level pressure lasting at least 24 hours and traveling more than 1,000 km.

Their analysis revealed that the maximum wind speeds of the most intense and impactful nor'easters, those above the 66th percentile, have significantly increased over this 85-year period. The storm's hourly precipitation rates also increased.

The researchers posit that these increases in intensity were likely fueled by the combined influence of higher ocean temperatures and the increased moisture capacity of a warming atmosphere.

The name "nor'easter" comes from the direction of their cyclonic wind patterns as experienced from coastal areas. These storms form when a cold, dry polar airmass descends from the north and encounters warm, moist air moving northward along the North American coast. The sharp temperature and moisture differences of these clashing airmasses is how they get their strength.

As a system of low pressure builds off the coast, it draws strength from the jet stream in the upper atmosphere. The system then builds and churns counterclockwise as it moves over warm waters in the Atlantic.

As it moves toward land, the storm brings with it a powerful storm surge and gale-force winds. Eventually, the storm either moves out to sea or continues on to the Canadian Maritime provinces, eventually weakening as the supply of warm, moist air is cut off.

According to the authors, "Our analysis of nor'easter characteristics reveals that the strongest nor'easters are becoming stronger, with both the maximum wind speeds of the most intense (>66th percentile) nor'easters and hourly precipitation rates increasing since 1940, suggesting an additional contribution to coastal risk in a warming world."

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