A massive winter storm pounded the Northeast early Friday with heavy winds and driving snow, shutting down Boston's airport, and prompting cancellations of thousands of flights as well as state emergency declarations in New York and New Jersey.
The onslaught was forecast to continue Friday with more heavy snow, howling winds and bitterly cold temperatures.
The National Weather Service said 21 inches of snow had fallen in Boxford, just north of Boston. Parts of Upstate New York had 18 inches. In Central Park early Friday, the National Weather Service said just over 3 inches of snow had fallen.
Nationwide on Thursday, more than 3,000 flights were cancelled because of the weather and over 10,000 flights were delayed, according to FlightStats.com. By early Friday, hundreds more flights had already been cancelled or delayed.
The worst weather is expected along coastal New England and on Long Island, where blizzard warnings are in effect until late Friday.
"What a New Year's gift, to receive one last snowstorm as mayor," said Boston Mayor Thomas Menino, who on Monday is leaving the office he has held for 20 years.
In New York, newly sworn in Mayor Bill de Blasio, who as public advocate in 2010 criticized his predecessor Michael Bloomberg for his handling of a post-Christmas storm, said hundreds of plows and salt spreaders would be on the streets.
"We have to get it right, no question about it," de Blasio said. "We are focused like a laser on protecting this city and getting everyone ready. We have all hands on deck."
The storm is expected to move off the coast by late Friday.
Share your snow pictures: How many inches did you get? Send us your snow photos
The Weather Channel reported late Thursday that at least 100 million Americans were under some level of winter storm warning, watch or advisory; the area stretched from southern Indiana to eastern Maine, a distance of almost 1,200 miles.
Snow fell throughout the day Thursday across the Great Lakes, the Northeast and New England. The heaviest snow fell in northern Illinois, where more than a foot of snow was reported late Thursday, according to the National Weather Service.
Winter storm warnings were in effect Friday in most of New York state, New Jersey, Massachusetts, Rhode Island, Connecticut, Vermont, New Hampshire, Maine and eastern Pennsylvania.
This included the entire New York City area, where 4 to 8 inches of snow was forecast. Gov. Andrew Cuomo declared a state of emergency across all of New York state on Thursday. Three downstate highways were slated to close at midnight. New Jersey Gov. Chris Christie issued a similar order and urged residents to stay off the streets.
"This is nothing to be trifled with," Cuomo said. "We have learned too well over the past few years the power of Mother Nature. We've seen the damage that can be done."
Cold facts: More record lows than highs in USA in 2013
Some schools in New England and New York closed pre-emptively Thursday, while cities issued parking bans and homeless shelters were expected to fill beyond capacity.
The storm was expected to dip as far south as Washington, which could get up to 2 inches of snow.
In Toms River, N.J., Jonas Caldwell said he was prepared for whatever the storm might bring
"Santa brought me a snow blower, and I've got rock salt for the ice, so now I'm just waiting for the storm," he said while grabbing a coffee at a convenience store.
Much colder air will reach the East on Friday, the weather service reported, with many areas seeing temperatures 20-30 degrees below normal. Some record lows are possible.
"This is likely to be the coldest weather for much of the Northeast since January 2009," according to AccuWeather meteorologist Bernie Rayno.
Lows in cities such as Philadelphia, New York and Baltimore will drop into the single digits Friday night while temperatures will drop below zero in Hartford, Conn.; Albany, N.Y.; Providence; Portland, Maine; and Boston.
Freeze watches and warnings have been posted all the way to northern Florida.
Wind chills could dip to as low as 19 degrees, prompting the weather service in Jacksonville to warn Floridians that "if you must venture outdoors, make sure you wear a hat and gloves."
In Green Bay, Wis., fans were preparing for a brutally cold NFL playoff game between the Packers and the San Francisco 49ers on Sunday afternoon, when temperatures are forecast to be below zero, with wind chills far below that. Temperatures could rival the famed "Ice Bowl" game of 1967, when the game time temperature was -15 degrees.
Contributing: Greg Toppo, Bart Jansen, William M. Welch, USA TODAY; Jon Campbell, Gannett Albany Bureau, Associated Press