My coldest commute so far has been about 15 F and I've done that several times. However, temps are supposed to drop to the single digits tonight with wind chills in the -5 to -10 range, so I will probably drive. I am not convinced that my gear -- mainly gloves and shoes -- will keep me warm enough in those conditions. Temperatures are supposed to be a little milder with no significant wind on Wednesday, so I do plan to ride that day and perhaps I'll set a new personal record low.