WASHINGTON: A blizzard could deposit up to three feet (90 centimetres) of snow on a large part of the US Northeast, the National Weather Service has said.

Almost 1,900 flights have been cancelled as the region braces itself for the harsh conditions.

The National Weather Service said the storm, known as a "nor'easter", would bring heavy snow, powerful winds and widespread coastal flooding through today.

A blizzard warning was issued for a 250-mile stretch of the Northeast, including New York and Boston. The storm promised treacherous travel by both land and air throughout the busy northeast corridor.

"This could be a storm the likes of which we have never seen before," New York City Mayor Bill de Blasio said at a news conference.

Along with the nearly 1,900 cancelled flights, nearly 1,800 additional flights have been scrapped today, according to the flight tracking site FlightAware.

Boston was expected to get 18 to 24 inches of snow, and Philadelphia could see 14 to 18 inches, the weather service said. The Washington area was expected to get a coating or a bit more.

In New York, transit officials planned to use modified subway cars loaded with de-icing fluid to spray the third rail that powers trains.