I like the snow. But -20 is my limit for non necessary winter activities. Way too many days spent shoveling snow in sorels and parkas. That's when I usually consider life choices like moving to oz or New Zealand.
What do you think we are? Freaks who bust out thongs at -10?!
I wear t-shirts at -20 if I'm just going from my truck into a store or work or something. Get your system used to it in November and you won't even feel the cold in January!!!
If it's -20 to -25 or so I'll usually board for about an hour and a half, grab a hot chocolate, go again, repeat. Below that you just have to shorten up the hot chocolate intervals!