[a-priori]

I grew up in Southern Ontario and when I was in high school I biked year round. I agree it's pretty rare that it's impossible to bike in the winter, and a good mountain bike should get you through pretty much any weather. The tires are the important part of the equipment.

But it can be downright unpleasant. Dressing right is the hardest part. If you don't do it right, your core will overheat at the same time you get frostbite on your hands. I had to wear ridiculous getups sometimes like touque, tube, heavy gloves, winter boots... and a t-shirt.