According to Wikipedia, the mean daily minimum of Helsinki in January is -5.6°. In Quebec City, it’s -17.7°. Not the same, at least according to Wikipedia.
Bike paths don't have to be dry though, you can sweep them and it's fine. If you use studded tires, you can ride a bike in places where you can't even walk. Source is I used to do this when I lived in the middle of nowhere in Sweden. I agree with you that infrastructure is key though. The temperature doesn't really matter, if you're good to go on a walk, you're also good to go for a ride.
I see bikes in the summer here. I dont see almost anybody biking in the winter here. Like 100:1. The winters here are not mild (like in vancouver). This is basically artic-like weather. People also tend not to walk. The very poor take the bus. Most drive.
