At least seven people died in weather-related accidents.
The severe weather has led the Foreign Office to update its advice to United Kingdom travellers in, or heading to, the region.
A man jogs on Memorial Drive during winter snow storm Grayson in Cambridge, Massachusetts, U.S., January 4, 2018.
More than a foot of snow was forecast for Boston and coastal areas of northern New England, with as much as 3 inches per hour forecast, a pace that made it hard for plow crews to keep roads clear.
Inland areas of the larger states should be free of concern outside of debilitating cold.
The worst of the storm will be over by Saturday morning, but the cold weather will continue.More news: Leonardo DiCaprio Will Headline Quentin Tarantino's Manson Movie
Through Thursday, parts of NY could see five to nine inches of snow, Philadelphia three to six inches and Washington one to two inches. (Credit: Aaron Lynett/Reuters) Pedestrians stop to photograph the frozen Josephine Shaw Lowell Memorial Fountain in NY.
A millibar is a unit of pressure measuring the weight of the atmosphere overhead, and is equal to about 0.0145 pounds per square inch.
Florida's governor Rick Scott urged people in the northern part of his state "to prepare for extreme cold weather conditions, including potential snow, sleet or ice accumulations". High temperatures will be mainly in the 50s through that time, with plenty of sunshine and not much wind.
Blizzard warnings stretch from North Carolina to ME, a day after snow fell in Florida's capital Tallahassee for the first time in three decades.
"We thought we were going to get six inches", said Brian Ireland of Plymouth.
Flooding from the storm surge was also affecting mass transit.
Ankle deep snow and wind gusts approaching 50mph covered Maryland's Ocean City Boardwalk, which was under a blizzard warning on Thursday.
The sharp drop in pressure means the storm is strengthening. The storm has also caused hundreds of auto crashes around the Tar Heel State, Cooper said. The Atlanta-based carrier has placed embargoes of varying lengths on a number of East Coast airports, including BOS, LGA, Charleston (CHS), Savannah (SAV), Providenc (PVD), Hartford (BDL), Norfolk (ORF), New York-JFK, and Newark (EWR).