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The latest of a series of weather systems to pummel the winter-weary eastern United States, the storm was expected to blanket the US capital with up to 23cm of snow as it swept from the Mississippi Valley to the Carolinas and Mid-Atlantic states, the National Weather Service said.
Brian Hurley, a weather service meteorologist, said temperatures would be about 15degrees Celsius below normal as a cold front gripped from the Great Plains to the Atlantic coast.
Although the snow is expected to bypass northern cities including New York and Boston, by early on Monday New York's temperature had already peaked at -5C, he said.
"This is yet another in a series of arctic outbreaks all winter," Hurley said.
Freeze warnings were in place from the Canadian border into Texas. The main electric grid operator for most of Texas issued a conservation alert due to expected higher power demand.
The storm shrouded the Capitol in snow and prompted the US government to shutter its Washington area offices, keeping hundreds of thousands of federal workers at home. Congress put off scheduled votes because of the bad weather.
The governors of New Jersey, Delaware, Mississippi and Tennessee declared states of emergency, and schools and local governments throughout the area closed. Maryland state offices shut down and West Virginia state workers were on a delayed schedule.
In Philadelphia's downtown Gallery mall, Juanita Thomas, 57, was waiting to go to her local bank, which planned to open two hours late due to the storm. She had no complaints about the repeated snowstorms that have clogged the city's streets and shut down schools.
"I wish it would have snowed on Christmas for my grandkids," Thomas said. "God's giving it all to us now."
About 2,250 flights were cancelled and 1,200 were delayed on Monday because of the storm, according to the airline tracking site FlightAware.com.
The worst-hit airport was Washington's Reagan National, where almost two-thirds of flights were called off. The ripple effect from cancellations and delays is expected to have an impact on air travel across the United States.
"Snowfall rates at the height of the storm may reach 5cm per hour, causing the snow to quickly clog major interstates," the AccuWeather forecasting service said.
At least two weather-related deaths, both from traffic accidents, were blamed on the wide-ranging storm over the weekend.
On the West Coast, a weather front will move onshore over the Pacific Northwest and northern California through Tuesday, bringing much-needed rain and snow to the region, the National Weather Service said.
Snow is also expected over parts of the Rocky Mountains and the northern Great Plains, it said.
A major highway linking Dallas to Houston, Interstate 45, was turned into a parking lot for hours on Sunday due to an ice storm that halted traffic.