It is a mild -10 degrees out. I went outside to see what it was like. I put on two tee-shirts, three sweaters, a hooded sweatshirt with a thermal lining, a wool trench coat, a ski mask, track pants under my jeans, and thick boots. I lasted about 10 minutes before every part of me was frozen. I'm not a little guy either. I'm pushing 200 pounds (i'm tall) and still it was more than i could handle.
Since i was in a ski mask, my breath bounced off and hit my face, so large parts of my beard were frozen to my to my face. I was picking ice out of my facial hair. So if it is -10 out, surprisingly, you should stay just stay inside and not go for walks. Who knew?
