A polar vortex is currently hitting the United States, with schools closed in many areas and at least four deaths caused by treacherous conditions.

A huge swath of the US was blasted with ice, snow and wind on Monday as the polar vortex that dipped south over the weekend kept much of the country east of the Rockies in its frigid grip, making many roads treacherous,

Parts of upstate New York saw 3 feet or more of snow from a lake effect event expected to last until late Sunday afternoon.

A huge swath of the U.S. was blasted with ice, snow and wind on Monday as the polar vortex that dipped south over the weekend kept much of the country east of the Rockies in its frigid grip, making many roads treacherous,

The polar vortex of ultra-cold air usually spins around ... Classes were also canceled in Maryland, where Gov. Wes Moore declared a state of emergency Sunday and announced that state government ...

The polar vortex of ultra-cold air usually spins around ... Brian Witte in Annapolis, Maryland; Julie Walker in New York; Joshua A. Bickel in Cincinnati; Jamie Stengle in Dallas; Jeff Martin ...

A winter storm could develop along an incoming Arctic cold front, increasing Maryland's chances of seeing accumulating snow.

A major cold blast is in store for millions of Americans as a lobe of a polar vortex will bring brutally cold temperatures to nearly every American east of the Rockies.

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

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.

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