I have commuted in temps at 15f degrees I do not mind the cold as long as I am dressed for it. I will stop along my commute if I get to cold, and go in a store to warm up for a few minutes.

Though last year I did get a flat tire on my way to work on a very cold morning(temp was about 20f degrees). I did not stop and change the flat as it was dark, and I was not taking off my gloves. I was very fortunate that I was about a mile away from work and could walk both me and my bike there.