I looked at the thermometer, and I saw why:
That's -18 Fahrenheit, also known as -28 Celsius, also known as holy crap it's cold! (Actually it showed -21 when it first got started, but I guess the roads were a bit warmer than the driveway, or the sun started coming up, or something.)
By the time I got to my office, an hour later, it showed a balmy -6 degrees. Oh yes, that's much better.