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.

A polar vortex dipping down from Siberia will bring a cold front with frigid temperatures to nearly 300 million Americans. See maps of the arctic blast.

There’s a chance of snow this weekend before temperatures are expected to drop to the single digits next week due to a blast of arctic air.

DES MOINES, Iowa (AP) — The plunging polar vortex brought subfreezing ... a weather service meteorologist based in College Park, Maryland. “We’re going to see areas of snow and ice start ...

The plunging polar vortex is bringing subfreezing temperatures to some of the southernmost points of the U.S. A forming storm system is threatening to dump snow on parts of Texas and Oklahoma, while communities in Louisiana and Florida may see frigid cold.

A snowplow clears the area as snow blankets Capitol Hill ahead of a joint session of Congress to certify the votes from the Electoral College in ... on Monday as the polar vortex that dipped ...

The plunging polar vortex is bringing subfreezing temperatures to some of the southernmost points of the U.S. A forming storm system threatens to dump snow on parts of Texas and

A huge swath of the U.S. was blasted with ice, snow and wind on Monday as the polar vortex that dipped south ... certify the votes from the Electoral College in the presidential election Monday ...

The plunging polar vortex is bringing subfreezing temperatures to some of the southernmost points of the U.S. A forming storm system is threatening to dump snow on parts of Texas

Texas has declared a state of emergency in response to the polar vortex. Maryland, Virginia, West Virginia, Kansas, Missouri, Kentucky and Arkansas have also declared a state of emergency.

The polar vortex is a ring of cold air that typically circles the Arctic. A strong jet stream essentially acts like a fence, keeping it locked there. If there's any weakening in the jet stream (the fence), the frigid air can become unstable and spill out. This sends the normally trapped cold air much farther south.

The polar vortex will extend into the metro St. Louis area Saturday, bringing several days of temperatures plunging to single digits and wind chills below zero.