What Is a Nor'easter? — In Plain Words

General information only.

The short answer

A nor'easter is a storm along the East Coast of North America.

It gets its name because the winds over the coastal area are typically from the northeast.

When they happen

These storms may occur at any time of year. They are most frequent and most violent between September and April.

Some well-known nor'easters are:

• The Blizzard of 1888.
• The “Ash Wednesday” storm of March 1962.
• The New England Blizzard of February 1978.
• The March 1993 “Superstorm.”
• The Boston snowstorms of January and February 2015.

How much damage they can do

Past nor'easters have been responsible for billions of dollars in damage. They have also caused severe economic, transportation, and human disruption, and in some cases disastrous coastal flooding.

Damage from the worst storms can exceed a billion dollars.

Where they develop

Nor'easters usually develop in the latitudes between Georgia and New Jersey, within 100 miles east or west of the East Coast.

These storms progress generally northeastward. They typically reach their maximum intensity near New England and the Maritime Provinces of Canada.

What they bring

They nearly always bring precipitation, in the form of heavy rain or snow.

They also bring winds of gale force, rough seas, and, occasionally, coastal flooding to the affected regions.

The heavily populated region between Washington D.C., Philadelphia, New York, and Boston — the “I-95 Corridor” — is especially impacted by nor'easters.

What feeds them

The U.S. East Coast provides an ideal breeding ground for nor'easters.

During winter, the polar jet stream transports cold Arctic air southward across the plains of Canada and the United States, then eastward toward the Atlantic Ocean. There, warm air from the Gulf of America and the Atlantic tries to move northward.

The warm waters of the Gulf Stream help keep the coastal waters relatively mild during the winter. That in turn helps warm the cold winter air over the water.

This difference in temperature — between the warm air over the water and the cold Arctic air over the land — is the fuel that feeds nor'easters.

Watches, warnings, and getting ready

Weather forecasters at National Weather Service local forecast offices around the country, and at the National Centers for Environmental Prediction near Washington, D.C., monitor conditions that are right for nor'easters, especially during the fall and winter.

When they see that conditions are favorable in the upcoming days, forecasters may issue winter storm, blizzard, high wind, and coastal flood watches. A watch alerts the public that some of the worst effects of nor'easters might be possible.

If conditions are imminent, those watches are changed to warnings.

Follow weather.gov to get the latest forecasts and warnings.

If a nor'easter threatens your hometown, the National Weather Service says to take steps to prepare, such as having three days of food, water, and other provisions in a disaster supplies kit. A nor'easter could cut power and leave you in the dark.

Also, sit down with your family and create an emergency communications plan, so your loved ones know how to stay in touch if you are separated.

Stay off the roads if advised by local authorities, and never drive into flood waters.

These simple actions will help you stay safe during a nor'easter.

A related page

See also this site's page “What Is a Bomb Cyclone? — In Plain Words.” A nor'easter can be a bomb cyclone, but the two words are not interchangeable: a nor'easter is named for its northeast winds and its East Coast setting, while a bomb cyclone is named for how fast a storm strengthens.

General information only.