Backyard Almanac: "Without -20, it's not really winter"
For Larry Weber, winter is about to arrive.
Air temperatures won't break zero through the end of the weekend, overnight lows will be in the double digits below, and the windchill index will hover around that strange point where the Celsius and Fahrenheit scales reach agreement: -40.
But there is a silver lining: Larry point out that these cold snaps usually only last about four days. So that's a mere 100 hours of "polar vortex."