The coldest weather conditions for two decades show little sign of relenting in parts of America, as forecasters predict freezing temperatures could make Tuesday the coldest on record in the 21st century.
It sounds like a plot device from a bad disaster movie, but for vast swathes of North America, the weather phenomenon known as a "polar vortex" has become all too real, bringing misery to millions across the US and Canada.
The blast of bone-chilling cold halted air travel, closed schools and prompted calls for people to stay inside.
Superlatives of cold-talk abounded, even in midwestern 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 travelers trying to head home from year's end holidays. More than 4,300 US flights were canceled Monday -- nearly half of those in Chicago -- and more than 6,500 were delayed, according to FlightAware, a flight-monitoring site.
At least a dozen people were reportedly killed in crashes on icy roads, including four people whose sport utility vehicle slid off a rural Minnesota highway and fell into the Mississippi River.
Comertown, Montana, recorded the lowest wind chill value so far at -63 Fahrenheit (-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 -29 Fahrenheit.
Even the typically temperate Deep South was feeling the chill with a hard freeze warning threatening crops and livestock. The mercury is likely to improve from mid-week, officials said.