It is there year round, but weakens during the summertime and strengthens in the winter.

The first cold wave will reach the East Coast on Thursday, followed by another surge of frigid air this weekend and more next week.

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

Meteorologist Eric Snodgrass says the storm hit 28 states with ice, snow and record breaking cold temperatures and the polar ...

Add Yahoo as a preferred source to see more of our stories on Google. Michigan is set for several days of frigid temperatures and heavy lake-effect snow as Arctic air continues its slow march across ...

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.

WASHINGTON (AP) — Warm Arctic waters and cold continental land are combining to stretch the dreaded polar vortex in a way that will send much of the United States a devastating dose of winter weather ...

Temperatures will start free-falling into the single digits after Friday morning, likely the deepest freeze so far this winter.

A Polar vortex has covered the Philadelphia region under a canopy of frigid temperatures, but many people may not realize what a Polar vortex actually is, and the dangers — like frostbite — such ...

Michigan is experiencing frigid temperatures and heavy snow due to a dip in the jet stream, not the polar vortex. The polar vortex is a large-scale cyclone of cold air that typically stays far north ...