CHICAGO: A historic and brutal winter storm put some 240 million Americans under weather warnings Friday as the United States faced holiday travel chaos, with thousands of flights canceled and major highways closed.

Heavy snow and howling winds upended holiday plans days before Christmas, as a huge cold front swept down from the Arctic and took freezing hold of much of the nation, including normally temperate southern states.

Wind chills brought temperatures below -40 degrees Fahrenheit (-40 Celsius) in some locations, with some 70 percent of the US population under winter weather warnings or advisories, according to the National Weather Service.

Meteorologists said it was so cold in places – 10 degrees Fahrenheit was recorded Friday in normally mild Dallas, Texas – that anyone venturing outside risked frostbite within minutes.

In Hamburg, New York, 39-year-old Jennifer Orlando hunkered down with her husband.

“We’re under a driving ban,” she told AFP, adding: “I can’t see across the street. We’re not going anywhere.” Her power was out for four hours after a RV (recreational vehicle) slid into a powerline on the highway, she said.

The biting cold is an immediate concern for some 1.5 million electricity customers, mainly in the US south and east, who were without power as of Friday morning, according to tracker poweroutage.us.

Transportation departments in North and South Dakota, Oklahoma, Iowa and elsewhere reported near-zero visibility, ice-covered roads and blizzard conditions, and strongly urged residents to stay home.

At least two traffic fatalities were reported in Oklahoma Thursday, Andy Beshear, governor of Kentucky, confirmed three in his state.

“Your family wants you home for Christmas, but they want you alive a lot more,” Beshear said to CNN.

Air travel chaos

Across the border in Canada, mercury plummeted as low as -50C (-58F) in the central province of Saskatchewan.

But last minute shoppers in downtown Toronto remained upbeat.

Jennifer Campbell, visiting from Caledon, Ontario, told AFP: “I think every few years we get some big storms and we just adjust. We are Canadians, that’s the way we do it.”

On the travel front, more than 4,170 US flights were already canceled Friday and another 4,650 delayed, according to tracking website Flight Aware, many at international hubs New York, Seattle and Chicago’s O’Hare.

The I-90, a major highway running across the north was shuttered in South Dakota, with officials saying it would not reopen until later Friday.

“Crews are using all available resources from across the state to clean-up and restore travel,” South Dakota Department of Transportation said.

Holiday travel volumes are expected to be close to pre-pandemic levels, with the busiest day on Thursday, three days before Christmas.

AccuWeather forecasters have said the storm could rapidly strengthen into what is known as a “bomb cyclone” through a process called “bombogenesis,” when the barometric pressure drops and a cold air mass collides with warm air.

Rapid frostbite

Such extreme weather can be dangerous, said Rich Maliawco, lead forecaster for the National Weather Service in Glasgow, Montana, where wind chill plunged to a bone-crushing -60 Fahrenheit overnight.

“When it’s this cold, anybody can run into trouble,” Maliawco told AFP.

“With these kinds of wind chills, if you’re not wearing those warm layers… unprotected skin can get frostbite in less than five minutes.”

Conditions were cold enough for people to post videos of themselves carrying out the “boiling water challenge,” where boiling water is thrown into the air and instantly freezes.

“We created our own cloud @ -17° F (-27° C) at the #Missoula International Airport,” tweeted NWS Missoula in Montana.