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

When the polar vortex stumbles, the weather at ground level can pivot from mild to brutal in a matter of days. A circulation ...

Thanks to the polar vortex, the first half of December will bring multiple waves of Arctic air to the U.S. Here's what to ...

(CNN) — High above the North Pole, in a slice of atmosphere rarely noticed and even less understood, a transformation is underway. Over the next 10 days, changes in the stratosphere will upend weather ...

The Polar vortex is causing temperatures to plummet dangerously across the Philadelphia region, and frostbite could become a ...

This coming weekend, the central and eastern United States will receive a blast of Arctic air, which will also affect ...

Winter is making its presence known in New York City, as the polar vortex is bringing brutally cold temperatures to the ...