Dangerously cold polar air snapped decades-old records as it spread through the US and eastern Canada, making it hazardous to venture outside and keeping many schools and businesses shuttered.
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Shelters for the homeless were overwhelmed and oil production could come to a standstill as the severe cold, described by some meteorologists as the "polar vortex" and dubbed by media as the "polar pig," brought temperatures below -27 degrees Celsius.
Monday’s (local time) bitterly cold temperatures broke records in Chicago, at minus 27 degrees Celsius, and Fort Wayne, Indiana, where the mercury fell to minus 25 degrees Celsius. Records also fell in Oklahoma and Texas.
Officials in states like Indiana already struggling with high winds and more than 30 centimeters of snow urged residents to stay home if they could.
‘‘The cold is the real killer here,’’ Indianapolis Mayor Greg Ballard said as he asked schools and businesses to remain closed another day.
‘‘In 10 minutes you could be dead without the proper clothes.’’
Officials were warning that the temperatures were "dangerously cold" and people should be aware of the risk of frostbite, which could take minutes to set in.
''I have seen frostbite occur through clothing,'' said Douglas Brunette, an emergency room doctor in Minneapolis. ''It's not enough just to be covered. You need clothes made for the elements. You need to repel the wind.''
Many across the nation's midsection went into virtual hibernation, while others dared to venture out.
New Zealander Ian Sutton, who is in Chicago for work, said it was a sunny, clear day despite the freezing cold.
"It isn't so bad walking with the wind, but walking into it with the windchill factor on your face, it is painful. We got 'brain freeze' after a few minutes," he said.
"I'm going to try to make it two blocks without turning into crying man," said Brooks Grace, who was bundling up to do some banking and shopping in downtown Minneapolis. "It's not cold - it's painful."
The polar air will next invade the East and South, bringing with it the prospect of more records falling.
Forecasters said about 187 million people in all could feel the effects of the "polar vortex" by the time it spread across the country.
"You definitely know when you are not wearing your thermal undergarments," said Staci Kalthoff, who raises cattle with her husband on a farm in Minnesota, where the temperature hovered around -31 and winds made it feel like -43.
"You have to dress really, really warm and come in more often and thaw out everything."
Even with this nostril-freezing cold, the family still prefers winter over summer.
"You can always put on more layers," she said. "When it gets hot, you can only take off so much."
Ronald Smith Sr took shelter at an Indianapolis Red Cross after waking up the previous night with the power out and his cat, Sweet Pea, agitated in the darkness.
"The screen door blew open and woke me up, and it was cold and dark. I got dressed and I was scared, thinking, 'What am I going to do? My cat knew something was wrong. He was jumping all over the place," Smith said. "This is brutal cold. The cold is what makes this so dangerous."
Between a heater that barely works and his drafty windows, Jeffery Davis decided he would be better off sitting in a downtown Chicago doughnut shop for three hours until it was time to go to work.
He threw on two pairs of pants, two T-shirts, "at least three jackets," two hats, a pair of gloves, the "thickest socks you'd probably ever find" and boots, and trudged to the train stop in his South Side neighborhood that took him to within a few blocks of the library where he works.
"I never remember it ever being this cold," said Davis, 51. "I'm flabbergasted."
Thousands of flights - one out of every 10 domestic departures - were cancelled. Airline officials said de-icing fluid was freezing, fuel was pumping sluggishly, and ramp workers were having difficulty loading and unloading luggage.
GETTING COLDER STILL
Temperatures were 11 to 22C below average in parts of Montana, North and South Dakota, Minnesota, Iowa, Wisconsin, Michigan and Nebraska, according to the National Weather Service.
The Arctic air was moving toward the east coast where temperatures were expected to fall throughout the day to about -18C, but they reached -25C. The coldest temperatures in years were expected in southern states.
"Cold temperatures and gusty winds associated with an arctic air mass will continue dangerously cold wind chills as far south as Brownsville, Texas and central Florida," the National Weather Service said.
The cold threatened to disrupt oil production, particularly in North Dakota, which could push fuel prices higher, analysts said. It also stalled shipments of grain and livestock and posed a threat to the dormant winter wheat crop.
In Cleveland, Ohio, where the temperature was -14C and was forecast to drop to minus -22C overnight, homeless shelters were operating at full capacity. Shelter operators had begun to open overflow facilities to accommodate more than 2,000 people who had come seeking warmth.
"There are also going to be people that won't go into the shelters," said Brian Davis, an organiser with Northeast Ohio Coalition for the Homeless.
The National Weather Service issued warnings for life-threatening wind chills in western and central North Dakota, with temperatures as low as -51C.
The frigid temperatures in the US mirrored or outdid those in such parts of the world as Almaty, Kazakhstan where it was -20C; Mongolia, where temperatures reached -23C and Irkutsk, in Siberia, where it was -33C.
From Minnesota, no stranger to cold weather, to normally warm Atlanta, unusually frigid conditions prompted scattered school closures. In Chicago, officials who had initially planned to keep schools open on Monday closed them after protests from the teachers union.
"It's a far cry from the days when our parents used to say 'I used to walk uphill both ways in a snow storm to get to school,"' said Oklahoma City filmmaker Cacky Poarch, 45, the mother of two children. "Now, we just say, 'It's cold. No school today.'"
Indiana was particularly hard hit. Offices and schools were closed in Indianapolis and businesses were asked to close at least until noon, if not all day.
Many people did not have the luxury of staying home.
In the western Chicago suburb of Geneva, Beth Anderson was shoveling the remains of Sunday's snow from her driveway before sunrise while warming up her pickup truck for the short drive to her job at a mall.
Anderson, 38, was well wrapped up against the bitter cold and was cheerful about the weather.
"I just wish I could get the day off too but it would take more than a bit of weather to close down the mall where I work," she said. Asked about the bitter temperatures, Anderson shook her head. "This is the Midwest, this is what winter is supposed to be like. It's been a while, so we were due for a cold one sooner or later."