(CNN) -- School administrators carefully watched weather forecasts Thursday night with some schools in the South opting to play it safe and cancel class or close early on Friday.
Forecasters at the National Weather Service are predicting 1 to 4 inches of snow for areas in the Ohio Valley and Mid-Atlantic regions on Friday with the Carolinas and Tennessee Valley getting freezing rain beginning early in the morning.
Schools in Raleigh, North Carolina, will close early, a spokesman with Wake County schools said.
"We're going to make sure we put a plan in place so that the buses are rolling while it's still safe and the students are back home before weather becomes an issue," he told CNN affiliate WRAL.
Dozens of school systems in Tennessee and some in northern Georgia said they would be closed.
Travelers were already affected Thursday night.
A spokeswoman for Nashville International Airport said all inbound American Airlines flights for Thursday night and Friday morning were canceled. Though she had no official word from other carriers, Emily Richard said she anticipated they also would cancel flights.
On the other side of the country, relentless freezing rain in Salt Lake City forced all of the runways at the city's international airport to close, according to the Federal Aviation Administration.
Road crews in the South were starting to prepare for the precipitation.
"Rest assured, our team is monitoring the winter weather and have been pretreating roadways across the Commonwealth," the Kentucky Department of Transportation said on its Facebook page.
How cold is it?
Brian Fitzgerald lives on top of a mountain billed as having some of the worst weather in the world, New Hampshire's Mount Washington. And with temperatures of 22 degrees below zero and wind gusts of up to 100 mph, it's living up to that reputation.
"It certainly makes getting out of bed very difficult," said Fitzgerald, who lives on the mountain eight days at a stretch as a weather observer for the private Mount Washington Observatory.
Wind chills on the mountain dipped to minus 85 on Wednesday.
"It's a constant blast in the face every time you go out," he said.
That's a sentiment millions of Americans might share at the moment, even if conditions aren't quite so extreme elsewhere.
In Waterville Valley, New Hampshire, the ski slopes were almost empty.
"The weather isn't quite cooperative, Drew Vetere told CNN affiliate WMUR. "It's a good day to get some hot chocolate."
People in the Upper Midwest who have been dealing with temperatures below zero are likely to have little sympathy.
"It is going to warm up to 20 by the first of next week and I can't wait," said Minnesota resident Margaret Davis in a comment on a CNN story. Temperatures for the morning commute in the North Star State stayed well below zero.
But as with most things, the cold is a matter of perspective ... or one-upsmanship.
"Temperatures as meager as -40 seems absurd," said reader Ben Edwards. "That's what one would call a warm day up here in Fairbanks, Alaska."
Not everyone was saddened by the conditions. Cathy Bryd, a third-grade teacher in King George, Virginia, got a day off and sent in an iReport.
"This is the first snow day of the season ... I'm sure my kids are definitely enjoying [it]," she said.
She said her dog, Toby, wanted to stay out in the freezing temperatures and play in the snow.
Cold weather tricks
The drop in temperature provided many with the opportunity to conduct some unusual experiments.
Several readers sent in submissions to CNN's iReport where they demonstrated the effects of the weather by tossing boiling water into the air and watching as the mist particles froze in midair.
A reporter with CNN affiliate KVLY in Fargo-Grand Forks, North Dakota, used a frozen banana to hammer a nail. It worked.
Others took soaking wet T-shirts, draped them on hangers and watched as the cold air quickly froze them stiff.
Chicago firefighters hosing down a burning warehouse blaze ended up encasing the building in inches of ice.
The cold weather was good news for those who sell hot coffee for a living.
"On days like this, coffee sells. Bagels don't," said Sami Akramia, a 41-year-old food cart worker bundled up in Midtown Manhattan as the temperature dropped to 4 degrees Wednesday.
National Weather Service forecasters say they expect the cold weather to last throughout the week and urged caution. The frigid weather can have deadly consequences.
Authorities say exposure to subfreezing temperatures left at least three people dead in Wisconsin, Minnesota and Illinois.
"Those people who work outside have to be careful," said CNN meteorologist Chad Myers. "We feel the wind chill, and so do pets. You need to find some place indoors and out of the wind for them."
In New York and New Jersey, homes destroyed by Superstorm Sandy in places such as New Dorp, Staten Island, and Far Rockaway, Queens, lacked basic utilities needed to restore heat.
In the northern Maine town of Presque Isle, temperatures hung around 24 below Fahrenheit. And in Grand Forks, North Dakota, residents bundled up to stave off a potentially deadly wind chill that hovered even lower, around 33 below.
"The biggest thing is staying out of the wind. That's what kills you," said Michael Lannen, who works at a Menards hardware store in Grand Forks.
"It seems we get one of these kinds of weeks every year, so everyone is just trying to bundle up and stay indoors."
CNN's Joe Sutton, David Ariosto, Christina Zdanowicz, Daphne Sashin and Rachel Rodriguez contributed to this report.