UK & World News
Polar Vortex: NFL Fans Brave -26C Wind Chill
Diehard fans have braved freezing temperatures and a wind chill of -26C (-14F) to watch an NFL playoff match in Wisconsin.
The Green Bay Packers took on the San Francisco 49ers at their home field on Sunday night, in one of the coldest American football matches ever played.
A phenomenon described as a polar vortex has plunged states in the north and northwest US into a deep freeze, causing transport chaos and school closures.
Fans at the Packers' Lambeau Field swaddled themselves in multiple layers of thick clothing and covered themselves with blankets for the tie, which lasted around three hours.
The 49ers' stars - who are more used to balmy California temperatures - wrapped up on the touchline in signature red blankets.
Despite not being accustomed to the inclement weather, they won 23-20, putting them one step closer to February's Super Bowl.
The weather phenomenon has seen super-chilled air from the Arctic sucked into North and South Dakota, the Great Lakes states and New England, sending temperatures plunging.
Washington DC has already seen its coldest temperatures for 20 years and several states in the Midwest have recorded their lowest mercury readings for more than a decade.
Icy weather is feared to have been a factor that led to a Delta Airways flight skidding off the runway at JFK Airport on Sunday.
None of the flight's 35 passengers was injured and the aircraft was safely towed to a gate.
The busy New York airport suspended operations for about two hours due to slick runways.
In Chicago, about 1,200 flights were cancelled at the city's O'Hare and Midway international airports after more than 11 inches of snow fell.
Weather Bell meteorologist Ryan Maue described the current weather conditions as a once-in-a-generation event.
"If you're under 40 (years old), you've not seen this stuff before," he said.
With much of the northeast of the country already under thick snow and well below zero, a newly emerging weather system is threatening to cause further misery.
The "polar vortex" is an anti-clockwise rotating pool of cold, dense air that forms close to the North Pole, but typically hangs over Canada.
Meteorologists say that unusually, this year, it is heading south and moving towards the north and eastern United States.
Fargo in North Dakota is expected to dip to -31C (-25F), International Falls, Minnesota, is forecast to fall to -35C (-31F) and Indianapolis, Indiana, and Chicago, Illinois, to -26C (-15F).
The forecast prompted Minnesota public school officials to announce a statewide closure for Monday, marking the first such mass closing in 17 years.
The Wisconsin cities of Milwaukee and Madison have also announced school closures to start the week.
Indianapolis Mayor Greg Ballard upgraded the city's travel emergency level to "red", making it illegal for anyone to drive except for emergencies or seeking shelter.
The last time the city issued such a travel warning was in 1978.
Temperatures are expected to dip close to freezing in parts of Florida on Tuesday.
In Canada, people have reported hearing loud booms which are thought to be "frost quakes" as temperatures dip to -20C.
The phenomenon, known as a cryoseism, is caused when water in the ground expands in extreme cold, causing it to crack and make the booming noise.
At least 16 deaths have been blamed on a snow storm that swept across the eastern half of the US at the end of last week.
Only a few thousand people have been left without power in the US despite heavy snowfalls, but in Canada, which has seen unusually heavy snow in a country used to cold winters, nearly 90,000 are without power in Newfoundland.
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