The sudden blast may come as a shock to many Americans after a mostly mild start to winter, but that warmth may be partly ...

A chilling polar vortex is set to bring snow and ice to the South and East this week. We show where.

The greater Philadelphia region will experience no weekend letup in the prolonged cold snap gripping the area.

The polar vortex will push Artic air south, and a severe winter storm could follow. How cold will it get in Louisiana?

A shift in the polar vortex has forecasters watching closely as the coldest air of the season approaches. Here's what to know ...

It exists all the time, but it usually gets stronger in winter. When the jet stream (a river of wind) bends and dips south, ...

With over 170 million Americans facing below average temperatures, even colder air may be on the horizon thanks to the displacement of the polar vortex that will lock in a deep winter feel and park ...

Don't let the incoming string of relatively warm days in the greater Philadelphia region fool you; the polar vortex is still around.

Much below normal temperatures should persist across the eastern U.S. into early February before moderating slightly.

As the U.S. prepares to take on another bout of cold weather, the term "polar vortex" is getting thrown around. But what is ...