-1 with a -19 windchill, but the sun was shining (a rarity here). It was amazingly nice. I was overdressed. I stopped to pull my balaklava over my face and accidentally fogged my glasses, which promptly froze. I rode without them, and it was fine.

This is my first winter commuting, and I've wanted to see how cold it could get before I was too cold to commute. At first I wondered about 30 degrees. Then 20. Now I'm not sure there is a bottom for mid-Michigan.