It looks like the polar vortex is letting up.  (Note: auto-play clip at link.)

Wednesday morning will still be unseasonably cold across the central and eastern U.S., with widespread subzero readings remaining in the Upper Midwest and Great Lakes. However, the temperatures won’t be quite as extreme as Tuesday morning.

In some areas winds will not be quite as strong as recent days, but over the Great Lakes there will still be a bit of a breeze. In any case, temperatures and wind chills will still be cold enough to pose a frostbite danger across most of the Midwest Wednesday morning, even if the numbers are not quite as extremely negative as Monday or Tuesday.