The first major winter storm of the new year barreled into the U.S. mid-Atlantic states on Monday, closing down federal offices and public schools in Washington, D.C., after dumping a foot of snow in parts of the Ohio Valley and Central Plains.

The extreme weather is being caused by the polar vortex, an area of cold air that circulates around the Arctic.

A massive winter storm poised to unleash a barrage of heavy snow, treacherous ice, rain, and severe thunderstorms across a 1,300-mile swath of the United States will affect an estimated 62 million people starting Saturday afternoon and continuing into Monday.