i've never really lost my temperment for cold since moving here from Alberta. -20 Still doesn't faze me, although I am getting kinda scared of -30 to -40 again.
Actually, the worst for me is between -5 and +5, because the air is still moist, and then the wind blows, and it sucks the heat right out of me. It its between 0 and -5 for a week, or lower than -10, then most the moisture disappears, and I can walk around in a t-shirt again.