A blast of bone-chilling cold has snarled air travel, closed schools and prompted calls for people to stay inside in the US and Canada, as temperatures plunge to lows not seen in two decades.
Superlatives of cold-talk abounded on Tuesday, even in mid-western states used to chest-high snow and bitter cold, as the National Weather Service said the deep freeze was making its way east.
Air travel was a nightmare, stranding many travellers trying to head home from year's end holidays.
More than 4300 US flights were cancelled on Monday - nearly half of those in Chicago - and more than 6500 were delayed, according to FlightAware, a flight-monitoring site.
Toronto's Pearson Airport halted ground operations early on Tuesday because of "equipment freezing" and out of concern for the safety of airport personnel, it said on its Twitter account.
Flights were scheduled to resume at 9am local time on Wednesday, but police were reinforced at the airport amid rising tension among stranded travellers.
Airline JetBlue said it was reducing operations at four airports in the bustling north-east corridor - JFK, La Guardia, Newark and Boston - until 10am on Wednesday.
More than a dozen deaths were blamed on the frigid weather.
A shift in a weather pattern known as the "polar vortex" triggered a drastic drop in temperatures to lows not seen in two decades.
It coincided with wind chill warnings in much of the eastern US.
Comertown, Montana recorded the lowest wind chill value so far at minus 53 Celsius, while North Dakota, South Dakota and Minnesota were not much warmer.
That was significantly colder than the South Pole, which recorded a wind chill reading of minus 34 Celsius.
In Minneapolis, Minnesota, where people scoff when cities like Washington, DC, panic and shut down with even a moderate snowfall, the newspaper The Star Tribune gave a graphic description of what happens when, for instance, the overnight temperature Monday hit minus 30 Celsius.
"The wind chill and cold are freezing exposed flesh in five minutes," it said.
The paper said life has "slowed to a crawl across the state".
"It's a blistering cold spell destined for Minnesota winter weather lore," it added.
Even the typically temperate Deep South was feeling the chill with a hard freeze warning threatening crops and livestock.
Chicago was among scores of towns and cities which told parents to keep their children at home rather than risk sending them out into winds so bitter that skin could freeze in a matter of minutes.
Illinois Governor Pat Quinn praised the "heroic" efforts of National Guard troops who cleared a 375-vehicle backup and a forestry officer who rescued seven stranded people and two of their pets using a snowmobile.
Indianapolis mayor Greg Ballard barred everyone except emergency workers from driving at the height of the storm on Sunday and urged residents to stay indoors unless absolutely necessary.
But with thousands of people without power after electrical lines were felled, home was not always the best option.
Those who couldn't stay with family or friends were urged to seek out community centres which were opened as temporary shelters.
The extreme cold disrupted flights and classes in Canada as well. The Atlantic island province of Newfoundland had more than 30,000 people without power.