Blizzards are expected across the area as the National Weather Service described the storm as "potentially crippling" for a huge swathe of the country, with near-record snowfall exceeding two feet (61 cm) in the Baltimore and Washington DC metro areas.
A blizzard watch was issued for New York City and parts of Long Island and New Jersey starting on Saturday.
Forecasters said up to 16 inches of snow.
The director of the National Weather Service Louis Uccellini said all the ingredients have come together to create blizzards with brutally high winds, dangerous inland flooding, white-out conditions and even the possibility of thunder snow, when lightning strikes through a snowstorm.
He said the storm could easily cause more than $1billion in damage and paralyse the East Coast.
It does have the potential to be an extremely dangerous storm that can affect more than 50 million people
Mr Uccellini said: "It does have the potential to be an extremely dangerous storm that can affect more than 50 million people.
“Washington looks like the bull's-eye of the blizzard, and New York City is just inside the slow-moving storm's sharp northern edge, which means it is likely to see heavy accumulations.”
Yesterday, thousands of flights were cancelled or delayed and residents stocked up on food and supplies as five states declared emergencies braced for the storm.
Millions of residents in the storm's path in Tennessee, North Carolina, Virginia, Maryland and Pennsylvania scrambled to prepare for the storm, clearing shop shelves of bread, milk and bottled water, food and other supplies.
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WASHINGTON POST
WASHINGTON POST
Federal employees in the Washington area were told their offices would close at noon today to allow them to get home safely before the snow begins piling up in the afternoon. Public schools have also been closed.
The Washington Metropolitan Area Transit Authority, which includes the second-busiest US subway system, took the rare step of suspending operations from late on Friday through Sunday.
The Virginia National Guard said it planned to bring in up to 300 troops to assist in response operations.
Airlines in North Carolina and Washington have also cancelled thousands of Friday and Saturday flights, with many of the 2,200 cancellations affecting travellers today.
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EPA
Washington Mayor Muriel Bowser and New York Mayor Bill de Blasio urged motorists to stay off roads amid icy and whiteout conditions.
The storm has also forced many to change their weekend plans, with Washington residents planning mass sledding events and a large snowball fight on Sunday.
New York cancelled its Winter Jam in Central Park, a winter sports festival set for Saturday, in anticipation of the storm.
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Icy conditions have already gripped large parts of the Northeast causing accidents that killed two drivers in North Carolina and one in Tennessee. A truck with a snowplough killed a pedestrian while it was snowing in Maryland.
AccuWeather Senior Meteorologist Alex Sosnowski said the storm taking aim at Washington could rank among the biggest snowfalls on record, eclipsing the Snowmageddon storm of 2010 that dropped 17.8ins.
The largest snowstorm in recorded history in Washington was the 1922 Knickerbocker storm, which buried the city under 28ins.