What Is a Nor'easter?

The Short Answer

A nor'easter is a storm that forms along the East Coast of North America. Nor'easters are named after the direction from which the strongest winds typically blow over the northeast states, including New England and the Mid-Atlantic states. The storms can bring wind, snow, rain and flooding to these regions.

houses and cars covered in snow as a person shovels a walkway.
Snowfall from a January 2015 nor'easter in Watertown, Massachusetts. Credit: Wikimedia Commons Aria1561 CC BY-SA 3.0

You've probably heard the term nor'easter in movies and on television, but what exactly does it mean? A nor'easter is a type of storm that forms along the East Coast of North America. Nor'easters are named after the direction from which the strongest winds typically blow over the northeast states, including New England and the Mid-Atlantic states. The storms can bring wind, snow, rain and flooding to these regions.

How Do Nor'easters Form?

U.S. map with a blue line labeled Jet Stream and arrows labeled northeast winds.
A nor'easter forms when cold air often originating in Canada blows over the warm Atlantic Ocean off the coast of the eastern United States. Credit: NOAA/JPL-Caltech

Nor'easters begin to form within 100 miles of the coast that stretches between New Jersey and Georgia. This area is a perfect spot for the formation of storms. The polar jet stream blows cold air southward out of Canada and eastward toward the ocean. The Atlantic Ocean is warm, thanks to the Gulf Stream–a warm ocean current.

Where the cold air and warm water meet, a low pressure system forms. The low pressure system causes clouds to form and a storm to develop.

What's the Difference Between a Nor'easter and a Hurricane?

Side by side satellite images of the storms over the U.S.

On the left, a nor'easter hits the East Coast on January 4, 2017. On the right, Hurricane Katia makes landfall in Mexico and Hurricane Irma passes between Cuba and the Bahamas on September 8, 2017. Both images are from NOAA's GOES-16 satellite. Credits: NOAA/CIRA (left) and CIRA (right)

Map of North, Central, and South America with hurricane and nor-easter paths highlighted in orange and blue.
Nor'easters form off the eastern coast of the United States (blue), while hurricanes are most likely to form in the tropics (orange). Credit: NOAA/JPL-Caltech

Upon first glance, the satellite images above might look very similar. However, if you look closely, you'll realize the spiraling storms in the photo on the right are much further south than the spiraling storm in the photo on the left.

Nor'easters and hurricanes both form over the Atlantic Ocean. They're both also types of cyclones–a storm that has winds spiraling around a central low pressure zone.

There are some key differences between the two storms. For example, hurricanes originate over the warm waters of the tropics–the region near the equator. Nor'easters originate further north, near the eastern coast of the United States. Also, nor'easters thrive and pick up strength from cold air in the atmosphere, while hurricanes thrive on warm air.

When Do Nor'easters Happen?

Black and white gif of clouds swirling over the north Atlantic
GOES-16 captured this video of a nor'easter traveling up the East Coast on January 4, 2018, producing strong winds and heavy snow. Credit: NOAA

Nor'easters can happen any time of year, but they are most common between September and April. They are most severe in the winter months.

What Kinds of Weather Do Nor'easters Bring?

If you hear that a nor'easter is headed your way, prepare for very bad weather. Nor'easters can produce heavy snow and blizzards, rain and flooding, and huge crashing waves. These waves can cause erosion to the beach and severe damage to nearby buildings and structures. Nor'easters can also produce wind gusts that are even stronger than hurricane-force winds.

How Do We Watch Nor'easters From Space?

Satellites keep a constant eye on Earth's weather, so they can take detailed images and measurements when severe storms strike. GOES-16, operating as NOAA's GOES-East, has a great view of the eastern U.S. Because GOES-East watches this region continuously, it can provide minute-by-minute updates of a Nor'easter's progress.

white, blue, red, and yellow clouds swirling over the Atlanic

This image of a January 2018 nor'easter was created by NOAA-20's VIIRS instrument, which is sensitive to changes in atmospheric temperature. In this thermal infrared image, blue and white indicate cold cloud tops, while the red and yellow shades indicate lower clouds and clear sky over ocean. Credit: NOAA