FOX NEWS / AP - Winter's sharpest bite in years moved past painful into life-threatening territory Tuesday, prompting officials throughout the Midwest to take extraordinary measures to protect the homeless and other vulnerable people from the bitter cold, including turning some city buses into mobile warming shelters in Chicago.
Temperatures plunged as low as minus 26 in North Dakota with wind chills as low as minus 62 in Minnesota. It was nearly that cold in Wisconsin and Illinois. Governors in Wisconsin, Illinois and Michigan declared emergencies as the worst of the cold threatened on Wednesday.
The U.S. Postal Service said it will not deliver mail in parts of the Midwest Wednesday because of the cold.
The bitter cold is the result of a split in the polar vortex that allowed temperatures to plunge much further south in North America than normal.
The National Weather Service forecast for Wednesday night called for temperatures in Chicago as low as minus 28, with wind chills to minus 50. Detroit's outlook was for Wednesday overnight lows around minus 15, with wind chills dropping to minus 40.
"These are actually a public health risk and you need to treat it appropriately," Chicago Mayor Rahm Emanuel said Tuesday. "They are life-threatening conditions and temperatures."
A wind chill of minus 25 can freeze skin within 15 minutes, according to the National Weather Service.
At least four deaths were linked to the weather system, including a man struck and killed by a snow plow in the Chicago area, a young couple whose SUV struck another on a snowy road in northern Indiana and a Milwaukee man found frozen to death in a garage.
Officials in large Midwestern cities including Minneapolis, Milwaukee, Chicago and Detroit were desperately trying to get the homeless off the streets.
Minneapolis charitable groups that operate warming places and shelters expanded hours and capacity, and ambulance crews handled all outside calls as being potentially life-threatening, according to Hennepin County Emergency Management Director Eric Waage. MetroTransit said it wouldn't remove people from buses if they were riding them simply to stay warm, and weren't being disruptive.
Emanuel said Chicago was turning five buses into makeshift warming centers moving around the city, some with nurses aboard, to encourage the homeless to come in from the cold.
"We're bringing the warming shelters to them, so they can stay near all of their stuff and still warm up," said Cristina Villarreal, spokeswoman for the city's Department of Family and Support Services.
Shelters, churches and city departments in Detroit worked together to help get vulnerable people out of the cold, offering the message to those who refused help that "you're going to freeze or lose a limb," said Terra DeFoe, a senior adviser to Detroit Mayor Mike Duggan.
Nineteen-year-old Deontai Jordan and dozens of others found refuge from the cold in the basement of a church in Ann Arbor, Michigan.
"You come here, you can take a nap, you can snack, you can use the bathroom, you might even be able to shower," he said. "And then they're feeding you well. Not to mention they give out clothes, they give out shoes, they give out socks."
Hundreds of public schools from North Dakota to Missouri to Michigan canceled classes Tuesday, and some on Wednesday as well. So did several large universities.
Closing schools for an extended stretch isn't an easy decision, even though most school districts build potential makeup days into their schedules, said Josh Collins, spokesman for the Minnesota Department of Education.
"Many students, they might have two working parents, so staying home might mean they're not supervised," he said. "For some low-income students, the lunch they receive at school might be their most nutritious meal of the day."
American Indian tribes in the Upper Midwest were doing what they could to help members in need with heating supplies.
Many people on the Standing Rock Sioux Reservation in the Dakotas live in housing that's decades old and in disrepair, or in emergency government housing left over from southern disasters such as hurricanes.
"They aren't made for this (northern) country. The cold just goes right through them," said Elliott Ward, the tribe's emergency response manager.
The extreme cold was "a scary situation" for the White Earth Band of Ojibwe, said Chris Fairbanks, manager of the northern Minnesota tribe's energy assistance program.
"We have many, many calls coming in. We're just swamped trying to get everybody what they need," she said.
The cold was even shutting down typical outdoor activities. A ski hill in the Minneapolis area said it would close through Wednesday. So did an ice castle attraction.
The cold weather was even affecting beer deliveries, with a pair of western Wisconsin distributors saying they would delay or suspend shipments for fear that beer would freeze in their trucks.
The unusually frigid weather is attributed to a sudden warming far above the North Pole. A blast of warm air from misplaced Moroccan heat last month made the normally super chilly air temperatures above the North Pole rapidly increase. That split the polar vortex into pieces, which then started to wander, said Judah Cohen, a winter storm expert for Atmospheric Environmental Research.
One of those polar vortex pieces is responsible for the subzero temperatures across the Midwest this week.
"We actually might see cold temperatures that we have never seen before or felt before across the Northern Plains," Fox News Senior Meteorologist Janice Dean said on "FOX & friends." "This is potentially deadly weather. You cannot be outside in temperatures like that. Your skin will freeze in minutes."
The Salvation Army was out in Chicago neighborhoods Monday handing out hot soup and warm clothes to people on the city's West Side. Major Nancy Powers with the Salvation Army told FOX 32 the concern is with the small percentage of the homeless population that refuse to come in from the cold.
"Just trying to get them not to freeze to death,” she said. “In this weather, believe it or not, at 20 degrees below zero, there are some folks who are still going to stay put."
Large crowds were already beginning to gather at one warming center on Monday as volunteers handed out supplies.
"I'm gonna survive by staying at the warming center and drinking hot cocoa,” one woman told FOX 32.
But some people who on the streets still plan to stay out in the arctic conditions. At a tent city on the southwest side of Chicago, George Arroyo told Fox News on Tuesday it was better to stay in his tent than go off to a shelter.
"A shelter is going to be crowded," he told Fox News. "Most of the shelters, they got bed bugs and we have heaters and plenty of gas. Ain't no sense to go to a shelter."
Arroyo told Fox News' Mike Tobin he had extra heaters in case the main heating supply in his tent goes out.
The extreme cold is also leading to school cancellations and travel disruptions throughout the region as officials prepare for its impact.
Minneapolis Public Schools officials have canceled classes through Wednesday, when the region is expected to experience frigid temperatures not felt for a quarter century. Hundreds of Michigan schools were closed Tuesday, including in Detroit, while Chicago Public Schools canceled Wednesday and Thursday classes because of the anticipated cold snap.
The Chicago Zoological Society said it was closing the Brookfield Zoo on Wednesday and Thursday — marking only the fourth time the zoo has closed during its 85-year history — to ensure the safety of its employees and animals.
At O'Hare International Airport in Chicago, the high temperature on Wednesday is expected to be negative 14 degrees, which would break a record set on Jan. 18, 1994. Hundreds of flights have been canceled at O'Hare and Chicago's Midway Airport on Tuesday due to lingering effects of the winter storm that hit the region on Monday, according to the Chicago Department of Aviation.
The cold will curtail Amtrak operations, with some scheduled trains between Chicago and St. Louis, Carbondale, Milwaukee and Detroit canceled due to the cold snap.
The U.S. District Court for the Northern District of Illinois will be closed Wednesday, in addition to several universities.
Cold weather advisories are in effect across a broad swath of the central U.S., from North Dakota to Missouri and spanning into Ohio. Temperatures will be as many as 20 degrees below average in parts of the Upper Great Lakes region and Upper Mississippi Valley, according to the National Weather Service.
"Some of the coldest air in decades will pour in across the Northern Plains, Midwest and Great Lakes with windchills in the -40 to -50 degree range and air temperatures below zero for several days," Fox News Senior Meterologist Janice Dean said Monday. "This will be dangerous and potentially deadly for these regions, and people need to stay inside."
At least 20 people have died in Cook County from cold-related exposure since the start of the season, the Cook County medical examiner’s office reported.