Major cities across the Northeast and Midwest are facing temperatures 10-20 degrees below average, according to forecasters.

A dramatic blast of cold air may be coming for the United States in late January, courtesy of the polar vortex. Here's what ...

In the coming weeks, cold air will continue for parts of the U.S. thanks to the influence of the polar vortex.

A fresh blast of Arctic air is poised to spill across a wide swath of the United States, and the latest polar vortex map ...

A fierce Arctic blast of bitterly cold air is poised to overtake much of the central, eastern and southern U.S. over the next ...

Each of these lobes of the Polar Vortex will bring two or three days of bitterly cold, below-normal temperatures. We aren’t ...

The polar jet stream, which is affected by the polar vortex above it, has become quite wavy, allowing Arctic air to ...

Repeated shots of cold air can be expected through the end of the month and into early February, according to AccuWeather.com ...

Add Yahoo as a preferred source to see more of our stories on Google. A map of the polar vortex that is bringing frigid temperatures to parts of the U.S. (AccuWeather) The first of three rounds of ...

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