(CNN) -- Get ready for bone-chilling cold you probably haven't endured in years.
A deep freeze is spreading across much of the United States this weekend, making the nor'easter that just blanketed about 20 states with snow look like a mere curtain raiser.
Nearly half the nation -- 140 million people -- will shiver in temperatures of zero or lower by Wednesday.
The arctic blast threatens to sweep subzero lows as far south as Alabama and plunge much of the Deep South into the single digits.
Winter weather in the past week has claimed at least 13 lives, CNN has confirmed.
Eleven people died in road accidents -- including one man crushed as he was moving street salt with a forklift.
A man in Wisconsin died of hypothermia. And in Byron, New York, a 71-year-old woman with Alzheimer's wandered away from her home Thursday night and was later found dead in the snow in a wooded area about 100 yards away.
The blast burst onto the stage in the northern Plains States early Saturday, hurling North Dakota into below-zero territory, as the National Weather Service predicted a day-long blizzard for the state.
Parts of Montana and Minnesota were feeling the same pain, the NWS said.
If there was ever a winter-toughened state, it's Minnesota -- but with this frosty bite on its way, schools in the state are keeping their doors shut on Monday.
"I have made this decision to protect all our children from the dangerously cold temperatures," Minnesota Gov. Mark Dayton said.
Saturday's temperatures will look relatively pleasant by the time we get to Sunday, as the thermometer falls to near 30 below zero in parts of North Dakota. And the wind will drive chills down to minus 50, the weather service said.
That's a recipe for rapid frostbite or hypothermia.
A 66-year-old man died of hypothermia in Milwaukee on Friday, the medical examiner's office said.
The weather service's Twin Cities, Minnesota, division warns, "Exposed flesh can freeze in as little as five minutes with wind chills colder than 50 below."
This system will produce "the coldest air in two decades," the service said.
The danger of injury and death from the cold will spread with the cold front into the Midwest by Monday night.
Power outages were not as widespread despite blizzard-level winds in some places when the nor'easter passed through in the last few days.
Sunday night in Chicago will see a shivering 16 to 20 below zero and -- once you factor in the Windy City's stiff breeze -- a chill of 35 below to 45 below zero.
Lambeau Field in Green Bay, Wisconsin, is unfortunately not a domed stadium. Fans and players there will be outdoors and brave temperatures approaching minus 20 as the Packers battle the San Francisco 49ers for a chance to advance to the Super Bowl.
Some sportswriters speculated that it may go down in the record books as the coldest football game ever played.
The Packers organization and a stadium vending company will serve free hot chocolate and coffee to help fans withstand the deep freeze.
As Packers head coach Mike McCarthy said Friday: "This is not the norm."
That's is not the only game where fans will brave the freeze.
On Saturday in Philadelphia, the hometown Eagles will host the New Orleans Saints in a playoff game. Fans can expect temperatures in the high teens or low 20s.
The Eagles' website urged people to show up early, as officials expect that fans bringing in extra blankets and clothing will slow down the security process.
As the arctic cold conquers about half of the continental United States, temperatures are forecast to dip into the minus teens through the lower Midwest. Snow will cover swaths from the Plains to the Ohio and Mississippi River Valleys, all the way to New England.
Parts of the Midwest could see temperatures not recorded in 15 to 20 years -- for a painful couple of days.
Even areas as far south as Nashville could be frozen solid in zero-degree cold as the arctic air mass dives southward at the beginning of next week.
Thousands were stuck at airports nationwide Friday because of system-wide delays -- though at least they are not out in the frigid cold.
FlightAware.com, which tracks cancellations due to weather and mechanical problems, said about 3,200 flights were canceled Friday within, into or out of the United States.
Expect more of the same in the coming days. Long before sunup Saturday, over 500 flights were canceled with half as many delayed.
Though the temperature in Las Vegas was 52 degrees -- above zero -- passengers there were also feeling the winter's sting Friday.
Long lines formed inside McCarran International Airport at the counters for Southwest Airlines, which had canceled many of its flights to and from Chicago. The airline carries 40% of Las Vegas' passengers, according to Chris Hayes, an airport spokesman.