The polar vortex is splitting — an exceedingly rare phenomenon for this time of year that will be an unusual driver of warmer temperatures, as the calendar flips to March and meteorological spring.

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

January has already been colder than average in most states east of the Rocky Mountains for the first time in two years - and now, more frigid air is coming. A lobe of the polar vortex, a stormy ring ...

Add Yahoo as a preferred source to see more of our stories on Google. Additionally, this shift in the jet stream will shield the East from the worst of the polar vortex, which will retreat farther ...

If you thought last week was cold, hold onto your hot lattes and be ready to bundle up as ( another ) winter storm is forecast to plunge arctic air deep into the Deep South by early next week. The ...

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 ...

While much of the eastern U.s. has been frozen by rounds of Arctic air and snow, the West has experienced weeks of unseasonable warmth, which has left many mountain ranges in a snow drought. A major ...

An Arctic air mass from Canada is bringing brutally cold temperatures to Michigan and the Northeast. Wind chills in Michigan are expected to reach as low as 10 to 20 degrees below zero. The cold snap ...

A lobe of the Polar Vortex is going to swing through Ontario just north of Michigan. The upper-air forecast gives us an easy look at this strong winter player. The general meaning of the Polar Vortex ...