Well I just got back from an experimental run. Temp was 7-12*f. I wore a medium weight merino wool base, and a light merino wool sweater (not as thick as my standard crew sweater), and wool pants. I was ok just standing around taking in the scenery, but got pretty hot when moving. Think I'll leave the sweater off and carry it in my pack. I had no idea that anorak would be that warm.