Temperature records dating back more than a century began to tumble in the Southeast early Thursday as a weather phenomenon known as the "Siberian Express" blanketed the eastern third of the nation in subzero temperatures.
Parts of Kentucky had already entered the record books by 4 a.m. ET, with almost all of the state between zero and -10 F according to The Weather Channel.
The cities of Paducah and Jackson were at were at -8 F and zero respectively — their coldest calendar dates since records began in 1895. They were the first of what meteorologists expected to be more than 100 record lows to fall through Thursday and Friday across the Southeast, Midwest, and East Coast.
More than 100 million Americans were set to be impacted by the arctic blast.
"The frigid air in the U.S. comes courtesy of the Siberian Express. It's cold Arctic air from northern Russia," The Weather Channel's Mike Bettes told NBC News. "It's traveling 5,000 miles over the North Pole, over cold snow pack, and going all the way as far south as the Gulf Coast."
Meteorologists said day records could fall in Kentucky, Tennessee, the Carolinas and Chicago on Thursday and in Boston, Washington, D.C., and New York on Friday. Meanwhile parts of Maine and New Hampshire could get more than six inches of snow through Saturday, according to the Weather Channel.
Emergency officials in southern states like Tennessee and North Carolina were asking the homeless to get to shelters as they prepared for potentially record-breaking temperatures 25 to 45 degrees below normal.
Chicago is experiencing its coldest February since 1875 and dealing with the threat of black ice — a thin coating of nearly transparent ice — on surfaces. In North Carolina, officials warned in a statement that scattered snow showers combined with below freezing temperatures could leave many secondary roads and streets in "ice skating rink-like condition."
"People still need to be cautious whether they are out driving or walking. The black ice is a very real threat and should be taken seriously," Public Safety Secretary Frank L. Perry said.
The Midwest, Tennessee Valley, southern Appalachians and the Northeast will likely get up to 3 inches of snow. But Maine, northern New Hampshire and northern Vermont could be hit by up to more than a foot of snow, The Weather Channel said. One town in the area, Eastport, Maine, has already been pummeled by 109 inches of snow in the last 23 days, according to The Weather Channel's Tom Niziol.
"It's pretty much overwhelming and we have another storm coming soon. It's going to be difficult," said Eastport's Police Chief Rodney Merritt. "It's going to be tough to handle."
More than 70 roofs have collapsed in Massachusetts, state emergency officials said. One of those was in Sutton, where part of a shopping plaza's roof collapsed Wednesday afternoon; no one was injured because the town had ordered an evacuation after some workers there said they heard cracking noises, NBC's Boston station reported.
At least seven people have died nationwide from hypothermia or car accidents attributed to the winter conditions.
In Cambridge, Massachusetts, five people were hit by snow falling off of the roof an ice rink on Wednesday, temporarily trapping four of them. Emergency responders had to remove one person stuck in the snow and they transported two people to the hospital, according to New England Cable News. Firefighters in Maryland's Montgomery County came to the rescue of a deer stuck in a frozen lake on Wednesday, NBC Washington reported.
Power outages hit some areas: Some 33,000 people in Tennessee were without power, while about 12,000 had no power in North Carolina, state officials said.
Some 1,300 flights were cancelled Wednesday; Amtrak is planning modified service on the northeast corridor due to extreme cold and weather. In Chicago, the city schools said they'd shutter Thursday, while others said they start late in anticipation of record-breaking cold and winds, NBC Chicago reported.
"The health and safety of our students is the district's top priority, and the extreme weather expected tomorrow could present real dangers," district leader Barbara Byrd-Bennett said in a statement.
NBC News' Tom Costello contributed to this report.