According to the National Weather Service, a polar vortex will impact most of the country this weekend, here is what you need to know.

A blast of Arctic air is set to cover much of the United States with temperatures below freezing starting on Friday and into next week, impacting millions of Americans in nearly all of the contiguous states.

It's going to get cold in Tennessee. Meteorologists predict freezing temperatures for much of the state. Here's the latest.

Some areas of the U.S. may see temperatures as low as -20 or -30 degrees early next week as arctic air from Siberia rolls in.

Americans were bracing Thursday for frigid temperatures that forecasters said could produce life-threatening conditions, with Donald Trump's inauguration expected to be the coldest in 40 years.

People living "basically anywhere from the Rockies eastward" will see extremely cold temperatures over the next several days, a meteorologist says. That includes Kansas City, which is set to host a Chiefs playoffs game this weekend.

The Siberian airmass, which is being spun southward by a stretching polar vortex, will keep temps 15 to 30 degrees below normal Friday night through Tuesday, perhaps stretching a bit later into next week. In the Twin Cities, the high temps Sunday and Monday might not reach zero.

The polar vortex is a large area of low pressure, winds, and cold air surrounding both of the Earth’s poles, according to the National Weather Service. The term “vortex” refers to the circulation of air that helps keep the colder air near the Poles. This vortex has always existed and is not something new.

Abnormal weather events and severe winter storms could be caused by a disrupted polar vortex. Find out here how the polar vortex affects the weather.