I live in Chicago so it drops down to about 20 in the evening on the average, and sometimes gets colder during the day. It's been a very warm winter so far which is why this hasn't been an issue yet. I ride every day no matter how cold it gets. My commute is about 15 minutes each way, and sometimes I bike for longer to get to certain places and whatnot.

I guess my issue with shoe covers is that they seem like a pain to get on and off the shoe and I imagine they don't function as well as an integrated shoe. I'm thinking about getting one of the northwave boots.