Running barefoot in the cold

I was very excited to get out and try running barefoot this morning. According to the thermometer on the side of my house, it was 28°F outside. I took my time to make sure I wasn't getting frostbite or anything. I got back after about 18 minutes and covered 2 miles. My feet felt cold but not terrible … the non-contact thermometer I have said they were around 60°F but warming up fast. After a few hours they felt fine. I suspect I'll only be able to run down to about 20° with no snow or wind, but we'll see.