A persistent weather pattern driving bitterly cold air south out of the Arctic will cause temperatures from Minnesota to Kentucky to plummet, turning this winter into one of the coldest on record in some areas.
Temperatures will remain in the grips of the deep freeze for two days, said meteorologist Mike Hudson of the National Weather Service in Kansas City, Missouri.
It would be similar to what happened earlier this month when temperatures dropped quickly and stayed low for days when a piece of the polar vortex - winds that circulate around the North Pole - ''broke off and moved south,'' Hudson said.
In cities where temperatures reached 4-10 degrees Celsius at the weekend, people will wake up Monday (local time) to temperatures ranging from -10C to -20C. And with the wind chill, cities throughout the Midwest will feel far colder than the -20C that Hudson said was expected in Barrow, Alaska, the northernmost US city.
The weather service said city after city would face wind chills well below -20C: -41.5C in Minneapolis, -25.5C in Kansas City, -23 .5C in St. Louis, and -19.5C in Louisville.
In the Chicago area, residents were bracing for a historic deep freeze. Monday's high was expected to be -20C and drop as low as -27C downtown, with wind chills as low as -40C).
Temperatures in Chicago could remain below -18C Tuesday (NZT Wednesday) as well and remain below zero for a total of 60 hours - the longest stretch since temperatures stayed below zero for a record 98 hours in 1983 and the third longest stretch in 80 years.
It also would easily eclipse the 36 straight hours temperatures stayed below zero earlier this month, when the frigid weather prompted the city's public schools to close for two days.
By noon Sunday (local time), Chicago's school district, which has about 400,000 students attending more than 650 schools, said it would be closed Monday (local time).
Severe weather conditions - with snow and high winds - were also impacting Indiana and Iowa.