I once encountered -30°F one winter in Fairbanks. I visited a hot spring where, for some cruel and unusual reason, the facility was designed so you needed to walk about 10 meters out of the (well heated) building to get to the water. And of course, you would do this walk in nothing but just your bathing suit. That was the longest 10m walk of my life.

The cherry on the cake of the experience was that you get into water that is 70+°F but every part of your body above the water line is exposed to -30°F winds. Fun!