Authorities warned that the extreme temperatures were life-threatening, as Illinois, Michigan, and Wisconsin implemented emergency measures.
The agency predicted temperatures to remain 25 to 45 degrees below average through Thursday, with wind chill values as low as -25 to -55 degrees Fahrenheit (-32 to -48 Celsius).
"We need everyone to do your part and make sure you and your families are prepared", said Illinois Governor JB Pritzker.
Thousands of flights were cancelled on Tuesday and further travel disruption in coming days is expected.
The National Weather Service warned of "life-threatening wind chills, likely leading to widespread record lows and low maximum temperatures" due to the arctic air mass intrusion which is now surging south into the Upper Midwest, which will eventually spread across the eastern two-thirds of the country later this week.
A forecast for warmer weather by the weekend offered little comfort to those enduring icy conditions, brutal winds and temperatures as low as minus 30 degrees Fahrenheit (minus 34 Celsius).
The polar vortex, which is when cold air high up in the atmosphere that usually lies over the North Pole moves down from the Arctic Circle, has already taken a deadly turn.
The cold front bringing its icy grip to parts of the USA and Canada is a result of a weather condition called a polar vortex.
Hundreds of millions of Americans spent Wednesday seeking relief from some of the coldest weather ever recorded in the continental United States.
'Emotional breakdown' as Japan stun imploding Iran at Asian Cup
The game was on a knife-edge but a misjudgement from Iranian defender Hossein Kanani tilted it Japan's way 11 minutes after half-time.
Unemployment on the rise due to Modi's 'pakodanomics': Kapil Sibal
The unemployment rate was much higher in urban areas with 7.8% rather than rural areas of 5.3%. And critics say the government's claims of economic success have sounded increasingly hollow.
Xiaomi’s Redmi Note 7 Pro to have 6GB RAM and 128GB storage?
Today we pitch the Zenfone Max Pro M1 with the latest entrants near its price point, the Redmi Note 7 and the Galaxy M20 . The Redmi Note 7 is ahead of the competition here too, coming with Android Pie 9.0 with Xiaomi's MIUI 10 on top.
Even if all-time records are not broken, the National Weather Service in Chicago is calling this week's forecast "life-threatening extreme cold" that "can lead to rapid onset of frostbite and hypothermia".
Lawrence Gottlieb of the University of Chicago Medical Centre said the threat was significant "when temps fall below zero, especially when there is a strong wind".
He tweeted: "In the lovely Midwest, windchill temperatures are reaching minus 60 degrees, the coldest ever recorded".
With the wind chill, it would feel like -40 or -50, officials said.
In Minneapolis, officials allowed residents to stay on public buses and trains for warmth. Conditions are particularly favorable for state records to fall this week, with clear skies and fresh snow on the ground. Cold weather advisories are also in effect across a broad swath of the central US, from North Dakota to Missouri and spanning into Ohio.
Nearly 3,000 flights have so far been cancelled including more than 1,550 in and out of Chicago.
An additional 200 flights were cancelled at Toronto's airport.
The shores of Lake Michigan near Montrose Beach in Chicago was a sea of white after a blast of Arctic air from the polar vortex brought risky, bone-chilling cold to a wide swathe of the United States on Tuesday.
Government scientists said increased moisture in the atmosphere because of global warming might bring on a higher number of severe snowstorms in the winter and more powerful hurricanes in the summer.