I rode today. It was 17 degrees when I left, wind chill around 10. I got too hot, tho, because I had on two wool sweaters, my wool coat and my ultra thick mittens and scarf. Had to undo the jacket halfway there.
I only have a 2.5 mile commute. I sometimes wonder if drivers think I'm a homeless person (there are more of them riding bikes in my city than bike commuters).