I actually ride all winter as long as the roads are not icy or snow covered.
I use layering under my windstopper jacket that is dependent on temperature.
This morning was not windy, just cold, about 30 or 32F. I wore leg warmers and tights on my legs, and a base plus fleece mid layer under the jacket. It was actually too warm as when I got back after 12 mile ride,I noticed that the base layer was wet from perspiration in the lower chest(beneath pecs) area. I assume this is because while the base layer wicks well, the fleece layer above it does not.
Anyway, I do bike all winter, at least down to the low 20's. Here in central NJ it is not often that cold during the day.
Best regards