Snow, high winds and a glacial chill hit the northeastern United States Friday as a blast of brutal wintry weather bore down on many states and major cities, snarling air traffic.
Temperatures in New York were expected to drop to 9 degrees Fahrenheit (minus 13 degrees Celsius), according to forecasts.
Tracking system FlightAware said that some 2,200 flights within, into or out of the United States had been canceled.
The National Weather Service issued winter storm warnings and advisories for a huge area spanning states from Chicago trough New York, New England and even the US capital, Washington.
Severe weather was also hitting the country's Midwest, dropping a blanket of snow and cancelling flights at Chicago's O'Hare International Airport.
The northeastern winter warning was in effect in New York from Thursday evening through midday Friday, with forecasters predicting four to eight inches (10 to 20 centimeters) of snow and winds that could reach up to 35 miles (56 kilometers) per hour.
New York City residents were urged to stay off the streets so the Sanitation Department could work.
Officials said that 450 salt spreaders had been out since early Thursday morning and 1,700 sanitation trucks had been outfitted with plows.
But Sanitation Commissioner John Doherty said that even with all the equipment the city had deployed, his agency faced a tough task as it worked to clear the streets through the night. He pleaded for patience, the New York Times said.
"A lot of people expect in New York City to see blacktop all the time," Doherty said. "It's going to take us a while."
The National Weather Service said blizzard conditions were possible for eastern Long Island and the coast of Massachusetts.
"Bitter cold will move into the Midwest and East following the storm," it warned.
In the Big Apple, where thick flakes fell Thursday evening, the storm will serve as a first test for the city's new mayor, Bill de Blasio, who assumed his post Wednesday.
De Blasio said the city had "laser" focus as it braced for what was to come.
"We are ready," he said.
He urged residents to stay indoors and use public transportation if they must get around. But, he warned, delays were to be expected.
"Please, starting this evening, stay inside. If you don't need to go out, don't go out," de Blasio said.
New York Governor Andrew Cuomo activated the State Emergency Operations Center and also urged people to use mass transit, warning of possible highway closures due to inclement weather.
In neighboring New Jersey, Governor Chris Christie declared a state of emergency in anticipation of what was to come.
Connecticut Governor Dannel Malloy, meanwhile, ordered state employees to leave work early on Thursday to alleviate the evening commute. Workers were not expected back at their desks until mid-morning.
Officials also warned about the risk of freezing or hypothermia due to the bitter cold that was expected to set it.
In Boston, where strong snowfall is expected until Friday, temperatures were expected to dip to minus 6 degrees Fahrenheit.
School classes and state offices were cancelled for Friday in Massachusetts.
Governor Deval Patrick urged businesses to do the same, so road crew could do the same.
"These circumstances are dangerous," he said Thursday night. "There is an even greater anticipated snow accumulation."
While the National Guard has been mobilized, Mayor Thomas Menino ordered public schools to close.
Airports across the region -- including Boston's Logan International -- saw major weather-related woes that were expected to extend into Friday.
At New York's airports, more than 500 flights were cancelled over the course of the day, with hundreds others delayed.