(CNN) -- Much of the country was in extremis Friday, with temperatures dropping to record lows in parts from Minnesota to Vermont.
A bank's sign in Plainville, Massachusetts, displays the temperature there Friday.
For those braving the deep freeze, the numbers ceased to have meaning.
"After it's 10 below, what difference does it make?" asked Wendy Schlueter of Babbitt, Minnesota, where the temperature hit 48 degrees below zero Friday
Schlueter, 54, took extra precautions as she prepared to care for her horses before going to work.
She put on non-slip boots, two turtleneck sweaters and long underwear, topped off by a fur coat.
"It's my big boy," she said. "When I go out, I'm not cold."
She fed the horses double rations of hay during the cold weather, and they don't appear to be suffering, she said.
"They pretty much eat nonstop. They've got a lot of hair. Right now, they're standing out in the sun and enjoying that."
Schlueter heats her house -- which has triple-paned windows -- with a wood stove, though last month's electric bill was $167.
The cold front stretched all the way into Florida and was forecast to dump heavy snow on the Ohio Valley, the Mid-Atlantic states and the Northeast on Friday.
The cold set records in Maine, Vermont, Michigan, Indiana, Illinois, Iowa and Minnesota, said Bruce Terry, a meteorologist at the National Weather Service's Hydrometeorological Prediction Center in Camp Springs, Maryland. Watch the freeze in Iowa »
St. Cloud, Minnesota's mark of 34 below was the same bitter low that was reached in Waterloo, Iowa. Terry said it also breaks the city's January record low temperature, which was set January 20, 1994, by one degree.
The meteorologist said record lows can be traced to cold air that has drifted from western Canada and Alaska, where Fairbanks had lows of between 45 below and 35 below last week.
"An area of low pressure allowed all this cold air to pour over the eastern United States and essentially dislodged that cold air and dumped it down into the central and eastern United States," he said.
By Friday, usual patterns had flipped. Fairbanks residents were basking in temperatures in the mid-30s while parts of the Tennessee Valley were shivering in the single digits, he said. Atlanta, Georgia, residents were bracing for temperatures in the teens again Friday night.
From the Upper Mississippi Valley through the Ohio Valley and in to the Great Lakes, temperatures will be at or below zero Friday night, he predicted.
The temperature in Chicago, Illinois, on Friday morning was minus 17 degrees Fahrenheit. And that didn't account for wind chill, which describes the combined effect of wind and cold temperature on exposed skin. Watch how people are dealing with the cold »
Jennifer Flesher, a 20-year-old CNN iReporter and student at the University of Illinois, said Thursday that the temperature was "unbelievable."
"I went outside to use the snow blower, and my lungs actually started hurting," she said.
Even by Minnesota standards, the weather is particularly brutal.
"You have to cover all of your skin, because you can get frostbite almost immediately. I have to go out every couple of hours to make sure all the pumps are working in our barn," said iReporter Leah Thomason of the Duluth area.
Thomason owns horses, which keep warm by standing in the sun and trying to get out of the wind. They also eat constantly to keep generating heat, she said.
"I have never seen weather like this before: individual icicles on each hair of the horses," Thomason told CNN. iReport.com: What's the weather like near you? Send photos, video
The National Weather Service said the bitterly cold temperatures are likely to remain in the East through the weekend, before more seasonable temperatures return.
Snow also fell Thursday in Trenton, New Jersey; New Haven, Connecticut; and other Northeast cities.
That wasn't bad news for everyone.
"I was in Killington, Vermont, and it snowed Wednesday through Thursday," iReporter Noel Abejo said. "Fresh powder! It was cold and windy, but I was on a snowboard vacation. Temps were in the single digits, and the winds made it feel like it was below zero. But I had a great time."
The National Weather Service offers the following guidelines for keeping warm:
The Weather Service also offers these cold weather dangers and warning signs:
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