At least 12 people have been killed during a brutal deep freeze wreaking havoc across the Midwest states of Michigan, Iowa, Indiana, Illinois, Wisconsin and Minnesota.
A wave of intensely cold air Arctic air sweeping across the US has sent temperatures plummeting to dangerously low levels and unleashed freak snowstorms in places.
A weather phenomenon known as a polar vortex is said to be causing the extreme conditions forecasters say have not been seen for at least generation.
Chicago, one of the worst affected cities, has essentially shut down after transport systems ground to a halt, schools closed and police warned of the heightened risk of accidents on icy roads.
A dramatic picture taken from an plane flying over Chicago shows how Lake Michigan has virtually frozen over in scenes reminiscent of sci-fi disaster movie The Day After Tomorrow.
Temperatures plummeted to -30C in Chicago, Illinois and -26C in Minneapolis, Minnesota, making parts of the US colder than the Antarctic.
Wind-chill temperatures in parts of the Northern Plains and Great Lakes plunged as low as minus -41C in Park Rapids, Minnesota, and -35C in Fargo, North Dakota, according to the National Weather Service (NWS).
Some 20 million people throughout America’s Midwest are expected to experience temperatures of -28C or lower by the end of the week.
The temperatures are so extreme, authorities and forecasters have said the cold conditions could induce frostbite and hypothermia within five minutes.
NBC forecaster Andy Avalos warned people in Chicago, where savage wind-chill will make temperatures feel like -48C, to refrain from going outside unless absolutely necessary.
“I cannot stress how dangerously cold it will be”
AccuWeather meteorologist Mike Doll
He said: “Wind chill values are -45F to -55F which could lead to frostbite and hypothermia in just a matter of minutes to any exposed skin.”
AccuWeather meteorologist Mike Doll said worse weather is yet to come as frigid winds began to blow into the US east coast on Wednesday.
“Some locations in the Midwest will be below zero continuously for 48-72 hours,” he said.
“I cannot stress how dangerously cold it will be.
“An entire generation has gone by without experiencing this type of cold.”
States of emergency have been declared in Midwestern Michigan, Illinois and Wisconsin, where as much as 24 inches (60cm) is forecast.
A number of multi-vehicle accidents happened in northeastern United States as dangerous snow squalls marked the arrival of brutal cold on Wednesday.
A huge 27-vehicle pileup in Wyomissing, Pennsylvania, left 24 people injured, two critically, on Wednesday amid ice and snow covered roads.
More than a thousand flights, close to two-thirds of those scheduled, were canceled on Wednesday into or out of Chicago O’Hare and Chicago Midway international airports. The Amtrak passenger rail service canceled all trains in and out of Chicago on Wednesday.
At least a dozen deaths related to extreme cold weather have been reported since Saturday in Michigan, Iowa, Indiana, Illinois, Wisconsin and Minnesota, according to officials and media reports.
In Detroit, a 70-year-old man was found dead on Wednesday on a residential street, a Detroit police spokeswoman said.
About 15 miles (24 km) south in the community of Ecorse, a former city councilman in his 70s and dressed only in sleepwear was also found dead on Wednesday, police said.
A polar vortex, a stream of air that normally spins around the stratosphere over the North Pole. has been disrupted and is pushing south.
National Weather Service (NWS) meteorologist Ricky Castro said: “This could possibly be history-making.”