A collapse in the polar vortex is letting Artic air come here. What that means, and why it happens.

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

Much of the nation east of the Rocky Mountains is hunkered down for what could be the worst winter storm of the season.

Temperatures could fall below -20 F across certain parts of North Dakota and Minnesota.

The meteorologists said the polar vortex system is set up due north of Michigan over Canada's Hudson Bay. It's at least ...

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

Meteorologists warn that a stretched polar vortex could bring severe winter weather to much of the United States ...

Tens of millions of people are in the path of a major winter storm. Federal cuts threaten efforts to understand the causes of such weather.

Rising Arctic temperatures and melting sea ice could be causing cold air to flow into the Northern Hemisphere. But not all ...

Starting Thursday, dangerously frigid air from Siberia and the North Pole is forecast to plunge the Great Lakes region into ...

After this weekend's snow storm moves out, cold Arctic air will move in.

Have you ever seen a 'steamnado' before? The Texas winter storm caused one to appear over Lake Lewisville on Sunday.