US northeast braces for monster snowstorm

The US northeast is bracing for a monster winter storm, with residents snapping up supplies ahead of what New York City's mayor warned could be a blizzard "the likes of which we've never seen before."

The stage was set for a possibly historic "nor'easter" that would affect an area from central New Jersey to the Canadian border from Monday to Wednesday, the National Weather Service said.

Officials in Boston, New York, Philadelphia and Washington urged residents to stay home as they prepared for a storm that could dump up to three feet (about a metre) of snow in some areas.

"We are facing most likely one of the largest snow storms in the history of this city," New York City Mayor Bill de Blasio told a news conference.

"My message to all New Yorkers is to prepare for something worse than we have seen before."

"Take every precaution, now is the time to get ready for this extreme weather," de Blasio said. "Don't underestimate the storm."

The US Weather Channel referred to the cold blast as a "possibly historic" winter storm, as airlines cancelled more than 1800 flights early on Monday as the weather system neared, according to flightaware.com.

Some airlines waved change fees as major delays and widespread cancellations were anticipated.

"This system will be responsible for heavy snowfall and strong winds, with blizzard conditions possible along coastal areas from New Jersey to Massachusetts," the weather service said.

"Many of the major metropolitan areas will be affected anywhere from Philadelphia through New York City and into Boston," it added.

Blizzard warnings were in effect along the coast from central New Jersey to the Canadian border.

People were scrambling to pick up storm staples such as shovels, road salt and ice scrapers.

"With a major winter storm approaching the state, I urge New Yorkers to take all necessary precautions and make preparations for the possibility that commutes will be disrupted on Monday and Tuesday," Governor Andrew Cuomo said.