I'm sad to say that due to climate change our normally chilly December now has 10 deg. C and rain... That's apparently 50 deg F.

Oslo doesn't really get that cold, but last winter I stopped cycling at -10-11 deg. C/12-14 deg. F, and I've only biked once in -13 deg. C/9 deg. F. Gets really hard to keep my feet warm!

Cross-country skiing in the mountains in -18-20 deg C/ around 0 F is no problem though, but my ski boots are a lot warmer and a lot roomier.