A polar vortex broke, and severe temperatures are set to dominate most of the United States, including the Midwest, in the coming days.

The blast of frigid temperatures follows days of snowy, icy conditions across much of the country. It's bringing the coldest air of the season so far to the Midwest and the Northeast. About 10 record lows are possible Thursday morning and 20 are likely Friday morning.

Tens of millions of Americans are under winter storm warnings as a "major" system is dumping snow and delaying flights.

The active December winter weather pattern continues across the United States. The Northern Tier will remain the primary focus for multiple rounds of clipper systems heading into next week. These systems will keep snowy conditions in place as cold air lingers across the region.

Such events distort the polar vortex, which causes Arctic air to descend into the U.S. and causes temperatures to plummet.

Chicago O'Hare International Airport is the most impacted airport by far, with over 700 cancellations and over 500 delays as of Saturday morning. Flights leaving to O’Hare are delayed an average of over five hours due to snow and ice, according to the FAA.

Midwest braces for frigid temperatures, significantly below normal for the season. Earlier this week, the states in the northeastern U.S. received multiple inches of snow, while the Midwest is bracing for the coldest temperatures of the season later this week.

Forecasters have said parts of the U.S. can expect frigid temperatures in December. A first round has arrived, and more cold air could be coming.

Black ice, snow showers and fog are pestering post-holiday travelers in the Midwest, while the Northeast is gearing up for its first major snowstorm of the season.

Another clipper system swings through the Midwest on Saturday afternoon will bring some quick snow accumulation to southern Minnesota.