The governors of Florida, Georgia, North Carolina and Virginia declared states of emergency, warning residents to expect icy roads and freezing temperatures. In the northeast, work crews loaded trucks with road salt in advance of the storm.
The New York City Department of Education said it would close public schools Thursday because of severe weather. The National Weather Service predicted New York could see 5-8 inches of snow and wind gusts as high as 50 mph on Thursday.
The cold has been blamed for at least nine deaths over the past few days, including two homeless people in Houston. Police in Roseville, Michigan, said on Wednesday that a 96-year-old woman, recently diagnosed with dementia, was found dead in a playground, apparently having frozen to death after wandering outside in a robe and slippers.
The National Weather Service had blizzard warnings in effect from Virginia to Maine, with areas around Boston expected to see about a foot (30 cm) of snow on Thursday.
"Bombogenesis," also known as a "bomb cyclone," occurs when a storm's barometric pressure drops by 24 millibars in 24 hours, greatly strengthening the storm.
The effect is seen along the Northeastern coast every winter, but this storm will be particularly powerful, said Judah Cohen, a visiting scientist at Massachusetts Institute of Technology.
"This one is unique in how quickly the pressure is going to fall," Cohen said. "The pressures could rival a Category 1 or Category 2 hurricane."
An arctic air mass will remain entrenched over the eastern two-thirds of the United States through the end of the week.
NOT FIT FOR MAN NOR BEAST
At a news conference, South Carolina Governor Henry McMaster warned people in the eastern part of the state to stay indoors if possible and to keep pets indoors.
In the state's historic city of Charleston, the winter storm shuttered carriage-horse tour companies after a horse slipped and fell on ice during a tour on Tuesday, city spokesman Jack O'Toole said.
The wintry mix and low wind chills caused widespread power outages and icy roads, making commuting treacherous for millions of Americans from northern Florida to southern Virginia, the National Weather Service said.
The storm was starting to snarl air travel in the southern United States, with about 50 percent of flights canceled at airports in South Carolina's Charleston and Myrtle Beach and Savannah, Georgia, according to the FlightAware tracking service.
Two to 3 inches (5-8 cm) of snow were expected in northeastern Florida, coastal Georgia and South Carolina, weather service meteorologist Bob Oravec said. The weather service said its Tallahassee office had measured snow and sleet accumulation of 0.1 inch (2.5 mm) on its roof, the first snow in Florida's capital since 1989.
Boston Mayor Marty Walsh ordered schools closed on Thursday, warning city residents that the peak of the storm would occur during the day, making travel extremely dangerous.
"Both rush hours will be affected," Walsh told a news conference. "Be patient. With the amount of snow we're getting here, we could be plowing your street and a half hour later it could look like we haven't been there."
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)
Get Breaking news, live coverage, and Latest News from India and around the world on NDTV.com. Catch all the Live TV action on NDTV 24x7 and NDTV India. Like us on Facebook or follow us on Twitter and Instagram for latest news and live news updates.