I have to add last night's ride to this conversation. Lisa hosted a HH for her trainees last night and need a sober ride home. So I jumped on the bike and rode nearly 7 miles at -6*F, into the headwind too. I wore the same stuff* I had on at my desk all day (home office), just adding my over-sized snowboard jacket, helmet, goggles, plus wool Buff, PI gloves, and 45NRTH boots. And it felt WARM ... 'cause it's all relative!
* stuff included wool long johns under Levis commuter jeans, long & short sleeve shirts under a hoodie, wool socks, and 'cause I'm bald, I keep my
45NRTH Greazy on all day in the house.