A blizzard pummeled the northeastern United States on Monday, burying cities in knee-deep snow, leaving thousands camped at airports and snarling traffic with blowing snow and icy roads at the end of the busy Christmas weekend.

New York City and surrounding areas were the hardest hit by the storm, which swept up the Atlantic Coast on Sunday night and continued up to the Monday morning commute, unleashing powerful winds and bringing cities to a halt.

At least a dozen traffic fatalities in several affected states were attributed to the treacherous road conditions. Winds gusted up to 59 mph.

Financial markets operated normally although trading volumes were thinned by the storm, which also kept shoppers away from the malls on the day after Christmas, one of the busiest shopping days of the year.

As the storm moved into Canada, the sun broke through on the U.S. East Coast, but massive piles of snow could take days to melt. Temperatures were not expected to climb above freezing for a sustained period until later in the week.

Authorities shut down New York's three major airports on Sunday night, canceling thousands of flights and stranding passengers in terminals that were cut off for hours from trains and taxis, with food and information in short supply.

The New York airports were due to reopen at 6 p.m. (2300 GMT) -- two hours later than initially planned.

"Here there are maybe 200 folding cots for 1,000 people," traveler Lance Jay Brown, 67, said from John F. Kennedy Airport's Terminal 8. "I paid $50 for three hot chocolates, a couple of candy bars and two sandwiches, and I was happy to get a sandwich. There are dozens of people twisted out of shape with frustration."

Major airlines including Delta Air Lines, American Airlines, JetBlue Airways, Continental Airlines and United Airlines canceled large numbers of flights.

One caller seeking to reschedule a flight on U.S. Airways was told by an automated phone message: "Your wait time is now 170 minutes."

Many offices closed for business, including the United Nations, which canceled all events at its New York headquarters.

After 17 hours of snowfall dropped 20 inches on New York's Central Park, the city was covered. Snow drifts piled 3 to 5 feet in some areas and giant mounds accumulated on the sidewalks where snow plows cleared the streets.

Similar snowfalls were reported throughout the Atlantic Coast, and totals reached as high as 29 inches in New Jersey.

"I'm just stunned by the power of nature," said Cheri Geckler, a neuropsychologist who was feeding animals at a stable in Lincoln, Massachusetts. "I worry about the impact on the human infrastructure and the livestock that we all depend on."

Skies started clearing just before the morning commute, providing ideal play conditions and an extra treat for children who either had class canceled or were on holiday from school.

SUBWAY SERVICE DISRUPTED

New York City subway traffic was sporadic and the commuter rails connecting the city to the suburbs were suspended.

One New York subway train was stuck on a frozen track for seven hours before the passengers were rescued. Transit authorities said they had to dig a towing locomotive out of the snow before it could the reach the stranded train in a remote area of the network.

Amtrak passenger rail service between New York and Boston was suspended on Sunday night but resumed with a limited schedule on Monday morning.

The New England states were also buried in snow. In Boston, only essential city employees were asked to report to work.

"I can't even find the sidewalk," said Marilyn Westgate, 44, of Belmont, Massachusetts, as she shoveled snow on her corner lot. "I don't even think about the time. I just do it."

In a sign of the severity of the storm, an NFL football game scheduled on Sunday night in Philadelphia was postponed, forcing the Philadelphia Eagles and Minnesota Vikings to reschedule the contest for Tuesday.

It was controversial considering the sport loves to glorify games in snow.

"It's an absolute joke," Pennsylvania Governor Ed Rendell, a big Eagles fan, told Fox News. "This is what football is all about. We're becoming a nation of wussies."