A "polar vortex" thrust the eastern two-thirds of the United States into historically frigid conditions. Even the southernmost states had wind-chill warnings.
"The coldest temperatures in almost two decades" spread into the northern and central parts of the country, packing gusty winds that produced "life-threatening wind-chill values as low as 60 degrees below zero," the National Weather Service said.
The extreme temperatures and blustery winds produced by the arctic cyclone created dangerously cold wind chills as far south as cenral Florida and Brownsville, Texas, the weather service said.
"This arctic air mass will affect the eastern two-thirds of the country on Monday as a sharp cold front moves toward the East Coast," it said. "The cold temperatures will remain in place through midweek before a warming trend begins."