Residents of the eastern and southern United States are battling dangerously cold air after a bitter front of frigid Polar air moved on from the Midwest.
The freezing temperatures have shattered decades-old records, making it dangerous to go outside and forcing thousands of schools and businesses to close.
Temperatures Tuesday plunged well below minus 10 degrees Celsius in Washington, D.C., New York, Philadelphia and Boston, while the wind chill, which is what the temperature feels like during a strong wind, is far lower.
The deep freeze has forced the cancellation of thousands of flights and created havoc on the roads and railways. Forecasters say nearly 200 million people could be affected by the so-called "polar vortex."
The frigid weather is also reaching into the so-called Deep South, including Florida and southern Texas, which usually enjoy moderate temperatures during the cold weather season.
Authorities have decided to close schools to keep children safe from exposure to the extreme cold, which could lead to frostbite within minutes if skin is left exposed.
On Monday, life-threatening cold paralyzed much of the Midwest. Air temperatures hit minus 27 degrees Celsius in Chicago and minus 29 in International Falls, Minnesota, colder even than the South Pole.
Forecasters say the polar vortex is a rotating mass of cold dense air being pushed south from its normal place in northern Canada.
More normal temperatures are forecast for later this week.