The snowfall is set to begin late on Friday and continue into Sunday
A massive blizzard which forecasters say could be among the 10 worst to affect the north-eastern US is poised to hit more than 50 million people.
Over two feet of snow has been predicted for Washington DC alone, with schools closed and flights cancelled and a state of emergency declared across a vast area.
National Weather Service meteorologist Paul Kocin compared the storm to 'Snowmageddon', the first of two storms that "wiped out" Washington in 2010 and saw 30 inches of snow.
Louis Uccellini, director of the weather service, said: "It does have the potential to be an extremely dangerous storm."
He said the elements look set to combine to create a blizzard with strong winds, dangerous inland flooding, white-out conditions and the possibility of thunder snow - when lightning strikes through a snowstorm.
The snowfall, which is set to begin late on Friday and continue into Sunday, could cause as much as $1bn in damage.
Mr Kocin said snowfall between one and three inches an hour could last for more than a day.
Up to 18 inches of snow is also predicted for Philadelphia, and up to a foot is forecast in New York.
A state of emergency has been declared in Tennessee, North Carolina, Virginia, Maryland, Pennsylvania, the District of Columbia and parts of other states.
Blizzard warnings are in place from Arkansas to as far north as New York.
Schools and government officers have been closed, thousands of flights cancelled and the shelves of stores emptied as millions of people stocked up.
Authorities have said the subway system in the capital will shut down entirely on Friday night and remain closed into Sunday for safety reasons.
Underground stations usually stay open during major snowstorms.
White House spokesman Josh Earnest said President Obama will hunker down at the White House.
Around 1,000 track workers will be deployed to keep New York's subway moving and 79 trains will be fitted with "scraper shoes" to reduce icing on rails.
All major airlines have issued travel waivers over the weekend, allowing passengers to re-book to avoid the storms. Flight tracking site FlightAware estimated at least 2,000 flights will be cancelled on Friday, and another 3,000 on Saturday.
Defences are being shored up along the East Coast.
Jersey beaches prepare for the worst and hope for the best, as towns build dunes to keep the sand from blowing into the roads , and the ocean wash off the boardwalkPosted by Belmar Beach NJ on Thursday, January 21, 2016
Meanwhile, grocery store shelves are emptying quickly as residents prepare for the storm.
What the grocery store looks like 2 days before snow fall in Virginia.Posted by Gary Brittain on Wednesday, January 20, 2016