Millions of Americans are set to be affected by the unusually cold weather, which will cause temperatures to plummet by as much 30 degrees in some areas. 

The blast of frigid air already descended on the region Monday morning, offering an early taste of winter - with snow seen in both Chicago and Michigan.

The weather in the region could last a week before relenting, warn meteorologists - who predict to see as much as a foot of snowfall in parts of the Great Lakes, Midwest, and New England as the mass moves down from Canada. 

Meteorologists meanwhile warn that freezing lows and killer frosts could extend as far south as Atlanta and Birmingham, Alabama, with temperatures in the upper 30s extending all the way down to the Gulf of Mexico.