To understand what Americans are experiencing with this winter blast, we need to look more than 20 miles above the surface of ...

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

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

During winter in the Northern Hemisphere, the polar vortex can often expand and send cold air south, often referred to as an ...

A Polar Vortex brought temperatures so cold in January 2014 that it froze Niagara Falls. Signals of a rare sudden stratospheric warming in the next two weeks have some forecasting an imminent Arctic ...

When the polar vortex stumbles, the weather at ground level can pivot from mild to brutal in a matter of days. A circulation that usually spins quietly above the pole can suddenly send lobes of Arctic ...

This winter’s harsh run is intensifying, with some of the coldest air so far this season plunging into New Hampshire.