In Minnesota, blustery weather could mean wind chills approaching -70. In Ponsford, the wind chill was -66, CNN meteorologist Michael Guy said.
It's so cold, the National Weather Service warned that frostbite could set in in just minutes.
CNN meteorologist Dave Hennen described it as the "coldest air in a generation." Temperatures will plunge to 20-40 degrees below zero between Tuesday and Thursday in the Upper Midwest, Hennen said.
In northern Minnesota, wind chills were forecast to drop to 65-70 degrees below zero, which would rival the coldest wind chill ever recorded in the state (71 below) in 1982.