On Friday, the National Weather Service (NWS) predicted dangerously low temperatures moving into the weekend as frigid air lingering over the North Pole prowls towards the US mid-Atlantic region.
"An arctic outbreak will keep temperatures 20F to 30F degrees below average across the north-eastern US," the NWS said, adding that there was a "chance for many daily temperature records to be broken".
In Massachusetts, residents of Boston, which received over 1ft (30cm) of snowfall, were clearing the streets with shovels.
It comes just days after a phenomenon described as a "bomb cyclone" brought heavy snowfall to a wide area along the US East Coast, as well as hurricane-force winds.
Giant waves caused by the storm saw freezing floodwaters inundate parts of the New England coast.
The extreme weather has so far been linked to up to 19 deaths in the US and two more in Canada, according to reports.
Four deaths were reported in traffic accidents in North and South Carolina. Further fatalities occurred in Wisconsin, Kentucky and Texas.
In Philadelphia, a car was unable to stop at a railway line at the bottom of a steep hill and was hit by a commuter train, killing a passenger in the vehicle.
In Virginia, a girl was fatally struck by a car while sledging, and a 75-year-old man was killed after being hit by a snow plough.
A 13-year-old girl died and 35 others suffered carbon-monoxide poisoning in an apartment building in Perth Amboy, New Jersey, where the temperature averaged 20F (-7C) on Thursday night. Seven of those treated were first responders.
The extreme weather caused travel chaos and led to the cancellation of thousands of flights on Thursday and Friday.
Most flights have since resumed at airports in New York and Boston.
Experts say the so-called bomb cyclone storm drew moisture and strength from as far south as the Caribbean Sea.
New Hampshire's Mount Washington, which boasts of having the "world's worst weather", was forecast to experience a wind chill temperature as low as -90F (-67C) on Friday night.
Law enforcement in the US state of Indiana issued a joke warrant for the arrest of the heroine in Disney movie Frozen, blaming her for the cold snap.
Queen Elsa is wanted for "maintaining a common nuisance", the Seymour police department said.
Atlantic and central Canada are being walloped by the winter storm.
The provinces of New Brunswick and Newfoundland and Labrador are both under winter storm and blizzard warnings.
On Friday morning, Nova Scotia Power said some 125,000 customers were still without power after 140km/h (87mph) wind gusts hit parts of the maritime province.
Power cuts have also been also reported in New Brunswick and Newfoundland.
Ontario is under an extreme cold warning, while Quebec faces heavy snowfall, strong winds and storm surges.
Boston harbour's tide gauge matched its record at 15.1ft - previously set during the great blizzard of 1978.
Flooding affected the city's newly renovated seaport district and deluged a downtown subway station.
Mayor Marty Walsh blamed climate change.
"If anyone wants to question global warming, just see where the flood zones are," he said.
The storm has so far forced hundreds of schools and businesses to close in New York City, Philadelphia, Boston, the Carolinas, Maryland and Virginia.
Panicked New York City residents rushed to shops before the snow came, clearing shelves of milk, eggs, and kale, the New York Times reported.
The weather pattern has already brought snow to the US South as far down as Florida, where the cold snap has caused iguanas to lose their grip and fall from trees.
Natural gas prices in the US north-east have risen to an all-time high, driven by demand for heating fuel.
BBC
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