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.

Salt only works above 15 degrees Fahrenheit. For colder temperatures, add a small amount of sand for traction or switch to an ice-melting product.

In central Ohio, temperatures will plunge from the low 20s to the low teens by midnight behind an arctic cold front, accompanied by snow showers and a few snow squalls that will leave a coating of snow and slick spots. Readings will fall to near zero by daybreak.

A polar vortex is slated to sweep most of the continental US bringing winter storm warnings and a hazardous freeze to millions.

COLUMBUS, Ohio — Today, most of central Ohio experienced its coldest morning of the winter so far. Here’s a map of the observed temperatures just before sunrise today.

Part of Mississippi under extreme cold warning after winter storm dropped snow across the Gulf Coast. When will temperatures warm up?

"That will actually linger for several days for much of the southern U.S., Ohio Valley ... to date will be due to a phenomenon called a polar vortex, an upper-level jet stream that typically ...

A polar vortex is slated to sweep most of the continental ... Snow will loom over much of the Appalachians, the upper Ohio Valley and the Northeast through at least Sunday, the weather service ...

Ohio Valley, mid-Atlantic and the north-east as we get into early to mid-next week,” he said. The coldest weather of the season to date will be due to a phenomenon called a polar vortex ...

Polar Vortex Set to Envelop Much of US in Freezing ... "That will actually linger for several days for much of the southern U.S., Ohio Valley, mid-Atlantic and the Northeast as we get into early ...

The polar vortex, a swirling mass of cold air located over the polar regions, is responsible for the cold. COLUMBUS, Ohio — An Arctic blast arrived in central Ohio on Monday, bringing with it the coldest air that central Ohio has felt in more than two years.

Research has found that rising temperatures in the Arctic are weakening weather systems that normally trap the cold around the poles, making winter weather more chaotic.