A new personal low temp commute today -31C (windchill -39C)... tomorrow might break it again with a forecast of -32C.
My mitts are a bit tight around the thumbs and they got cold, but fingers stayed warm. I do need to solve this fogging glasses problem and pick up some goggles or a ski helmet with built in visor/goggles. Right now my cheeks and eyes get pretty frosty, because I can't pull a face warmer up over my nose because my glasses immediately fog and then frost up. Otherwise I was probably overdressed, but that was by intention. I wanted to be able to walk if my bike gearing failed me. The IGH was sluggish (it took time with no pedaling the shift), but otherwise the bike worked great! Dynamo lighting, braking (rim brakes) were all good.
The coldest time is really the time required without mitts to lock and unlock: doors, bike cage, bike lock etc.