Just how cold is this week’s mid-western polar vortex get?  On Wednesday, it will be colder in Chicago than in Antarctica, Siberia, or the top of Mt. Everest.

Local forecasters are predicting temps to reach a record low of 20 below zero on Wednesday.

it won’t just be the Windy City – more than 90 million people in the U.S. will experience below-zero temps this week.  John Gagan with the National Weather Service is calling it ‘once in a generation’ cold.