THE United States is spending the first days of 2014 in the grips of record-breaking cold and snow as a "polar vortex" of freezing Arctic winds sweeps across the country.
Around 140 million people -- slightly less than half of the American population -- were set to face sub-zero conditions as the aptly-named winter storm Hercules overran the northern states and threatened to push into the usually-balmy Deep South.
In Minnesota the temperature was predicted to reach --35C but meteorologists warned that accompanying wind chill could make it feel twice as cold, bringing frostbite to exposed skin within minutes.
Eleven people have died in weather-related incidents in the last week, including a 71-year-old woman with Alzheimer's who wandered away from her home in upstate New York and was found frozen to death in woods only 100 yards away.
American football fans were layering up for what is expected to be the coldest game in recorded history when the Green Bay Packers take the field today against the San Francisco 49ers in --46C conditions.
The extreme weather began last Thursday with blizzards of snow across the north-east, dumping nearly two feet onto areas around Boston and parts of New York.
The deluge of snow has led to around 4,000 flights being cancelled, including many transatlantic ones. Thousands of stranded passengers were curled up in hallways of New York's airports as they waited for conditions to improve.
But the real cold is expected to set in tonight when a "polar vortex" of freezing, dense air that has collected at the North Pole will reach the American mainland, meeting already frigid conditions on the ground.
"All the ingredients are there for a near-record or historic cold outbreak," said one meteorologist. "If you're under 40, you've not seen this stuff before."
Schools across the northern US have already been closed for the first part of the week. Though the cold spell is expected to pass within days, its effects could linger, including freezing over the Great Lakes on the Canadian border, which could exacerbate cold weather for weeks to come.
The cold is expected to drive as far south as Florida, where temperatures in the single digits are almost unheard of and few own serious winter clothes.