People in much of the United States are dealing with cold weather not seen in 20 years.
The National Weather Service is calling the polar air mass sweeping across the country "dangerously cold," and has posted wind chill warnings for Monday that stretch from North Dakota to New York in the north and as far as Alabama in the deep south.
The mayor of Indianapolis in the central part of the country, Greg Ballard, said the extreme temperatures are life-threatening.
"This weather combination that we are seeing right now with all of the snow and the cold is unlike anything that we've seen in decades in this area and I can't emphasize that enough. The cold really scares me and as such that we will have temperatures that are potentially deadly or certainly look (like) life-altering temperatures.''
Carl Erickson, a forecaster with AccuWeather, told VOA that wind chills in major East Coast cities could reach 20-to-30 degrees (Celsius) below zero, while in places like Montana and North Dakota those figures could hit minus 50 degrees.
"The good news is, although this is a very intense cold air mass system that we haven't seen in decades, it will not be long-lived. Even as we go into Wednesday the winds will begin to lessen, the cold air eases, and although no big warm-ups it will definitely feel a little bit better Wednesday compared to the next couple of days. Going into Thursday and Friday, looks like temperatures actually rebounding to near average levels, probably in that 5-to-10 degree above zero range in the big cities by Thursday and Friday."
The cold and fresh snow measuring more than 30 centimeters in some places in the Midwest have created dangerous travel conditions, forcing schools to close and airlines to cancel thousands of flights.
Forecasters say the widespread chill is the result of a relatively infrequent alignment of weather conditions, allowing a so-called polar vortex to travel unusually far to the south from its normal place in northern Canada.
A polar vortex is a counterclockwise rotating pool of cold, dense air. It is expected to knock temperatures in half the nation down to minus 17 degrees by Wednesday.