As long as the roads are dry and the temp is above freezing when I leave for work (~7:30) I ride, year round. Generally speaking its rare that I go more than a week to ten days without being able to ride to work - and wet, sandy/salty roads probably eliminate more days than low temps.
Admittedly it takes me awhile when the temps drop - mid-thirties still seem too cold right now, but by December I won't think anything of it. I am thinking of better, if not heated, gloves and a helmet with better ventilation to reduce fogging up.
