So cold that on a quiet night, that when you take a hot cup of coffee and throw it in the air. You’ll hear a weak crack sound and the coffee turns instantly to snow before drifting to the ground. (-40F)
So cold that the snow covered roads are no longer slippery.(-20F) (Its like driving on something similar to hard compacted dirt – watch out for where a car has been idling though, like at the stoplights).