The New York City area was placed under a 35-hour blizzard warning beginning Monday afternoon, with more than 2 feet of snow expected to create "paralyzing, crippling" conditions, forecasters said Sunday.
It's part of a storm system that's expected to pummel the Northeast from Philadelphia all the way to northern New England with potentially "historic" snow accumulations well into Tuesday night.
The National Weather Service estimated that 29 million people will come under the blizzard warning, which covered a 250-mile stretch of the Northeast. Almost 1,900 flights scheduled for Monday were canceled, and almost 1,800 for Tuesday were scrapped ahead of time.
The worst of it will be late Monday through Tuesday night, with blizzard conditions, damaging wind gusts to possibly hurricane strength and coastal flooding, the National Weather Service said. The nation's largest city was put under an extraordinarily long blizzard warning stretching from 1 p.m. Monday to midnight Tuesday.
The forecast means New York City could smash its one-day snowfall record — 26.9 inches, recorded in Central Park in February 2006.
"Very highly populated areas of the Northeast are going to get crushed with snow," said Tom Moore, coordinating meteorologist for The Weather Channel. "Everywhere ... you're going to get hit very hard by this storm."
"This could be the biggest snowstorm in the history of this city," Mayor Bill de Blasio told reporters Sunday. "My message for New Yorkers is prepare for something worse than we have ever seen before."
New York Gov. Andrew Cuomo urged people to stay at home and said potentially dangerous conditions could mean shuttering the New York City subway, suburban commuter rail services and buses, as well as major roads, like the Long Island Expressway. Many school districts were letting students out early on Monday in the New York City area.
"This is going to be a big one, historic," The Weather Channel's Moore added. "There could be paralyzing, crippling blizzard conditions."
Moore said travel would be "dangerous if not impossible." Many airlines declared winter weather waivers, allowing passengers in the Northeast to change itineraries without a fee.
Moore said New England was "going to take a big hit, for sure," with the storm intensifying "into a monster" as it moves northeastward Monday.
In Boston, crews were stocking their plows with salt and sand for clearing snowy, icy roads. Officials cautioned that heavy and wet snow could trigger power outages, NBC station WHDH reported.
"Take this very seriously," Mayor Marty Walsh said. He urged city dwellers to get prepared as soon as possible. "Don't wait till the last minute, because this storm is giving us a 24-hour head start to get ready for it."
Massachusetts was also bracing for winds that could reach 70 mph in coastal areas, which, paired with the snow, will create whiteout conditions. That will likely mean some time off for hundreds of thousands of workers.
"Now it's going to all come. February is a snow month, and I can't wait," Debora Labonte of Chicopee, Massachusetts, told NBC station WWLP of Springfield. "I went to the grocery store and picked up a few items getting ready to maybe stay home from work.
The Super Bowl-bound New England Patriots expected to be out of town by the time the storm arrives in Boston. The team plans to leave Logan Airport at 12:30 p.m. Monday for Phoenix, where the temperature will reach the high 60s.
The forecast came after millions of Americans across the Northeast awoke Saturday to a blanket of snow that was later doused with rain, leaving New York, New Jersey and Pennsylvania in a sloppy mess.
New Jersey State Police reported 126 traffic accidents, and a parking garage in Secaucus collapsed under the weight of the snow and a plow, police said. The plow's driver suffered minor injuries in the accident, which created a hole that was 50 feet by 50 feet, NBC New York said.
A Nor'easter delivered more than 5 inches of snow in New York City, while residents of northern New York were digging out of as much as 9 inches, NBC New York reported. Saturday's storm was the first significant snowfall in the New York area this winter. Scott Flath, general manager of Long Island Hardware in Bohemia, New York, said his store is well-stocked but that many of his customers are making their first winter supply runs of the season. He said they're telling him, "I have no idea where my shovel for last year is."
NBC News' Alastair Jamieson and The Associated Press contributed to this report.