Parts of U.S. abruptly thrown into early winter as cold snap sweeps through (PHOTOS)

WASHINGTON -- An early blast of cold air will leave more than half of the United States shivering into the weekend.

About 200 million people will be affected by the severe cold, CNN meteorologist Pedram Javaheri said.

The unseasonably cold temperatures associated with an arctic air mass will continue to surge southward through the central United States.

Temperatures are forecast to be 20 to 40 degrees below climate average for areas east of the Rockies into the Great Plains.

The cold air will move toward the South by Wednesday morning, bringing freezing temperatures as far south as Oklahoma and the Texas Panhandle.

It will reach the East Coast by Thursday, forecasters said.

"Early season cold outbreak will drift south and eastward across much of the eastern half of the country over the next several days," the National Weather Service said in a statement.

By the time the weekend hits, hardly anyone in the eastern two-thirds of the nation will be spared.

"The next 10 days over the entire eastern half of the country will be below normal," CNN meteorologist Chad Myers said Tuesday.

In Wyoming, the wind chill is expected to be between 25 to 35 below zero. Experts warned residents not to stay outside for prolonged periods, and urged farmers to move livestock into a barn.

"The cold spell is about zero degrees, and we will get subzero overnight," said Mayor Rick Kaysen of Cheyenne, Wyoming.

Hiatus from the outdoors

Residents flocked to grocery stores to stock up as they anticipated a hiatus from the outdoors.

"People are hunkered down at home, maybe sitting around the fireplace," Kaysen said. "This is not unusual for us, except that maybe it is early on in the season. We have experience with it. There was advance information coming in regard of the intensity of the storm and what to expect."

In Minnesota, though tempered by years of long brutal winters, this snap came a little too soon.

"This is the first snow I've seen this season, and it's a major snowstorm, rather than the usual light dusting you'd expect to start off the winter with," said Katie Robinson of St. Paul.

"I think that's the biggest thing -- that we went from a very warm and mild fall to now being thrust so abruptly into winter."

In Montana, temperatures plummeted as bitterly cold winds rushed down the front range of the Rocky Mountains.

In Billings, Wednesday will bring overnight lows below zero and daytime highs in the single digits.

With overnight temperatures plunging close to record lows, downtown Billings, the heart of Montana's largest city, was empty.

Those who did venture out in the cold said they were ready.

"We just watched the alerts, and when they say it's going to be cold, we just bundle up," resident Tessa Rogers said.

South will get hit too

The cold snap will bring lows in the teens and single digits into Iowa, Kansas and Colorado this week but also spread freezing temperatures as far south as Texas. A hard freeze warning extends to just north of the Dallas-Fort Worth area.

The frosty blast will move across the rest of the United States, but it will not be as harsh as in the Midwest.

Atlanta and Birmingham, Alabama, are expecting daytime high temperatures in the mid-40s on Friday, according to the National Weather Service. A normal high this time of year is 64.

How did this happen?

Residents in the northern United States can thank Super Typhoon Nuri for the mess.

It is the strongest post-tropical cyclone on record in the North Pacific, the NWS said.

The storm system plowed into all that arctic cold air in Alaska and northern Canada, forcing it south.

Things will get warmer over the weekend, but it won't stay that way, forecasters say.

Another arctic blast is on the way for next week.