Several of my club members fly all winter (me included) -- & winter is the real deal here. I generally avoid flying at temps lower than minus 15 -- the wind is like a knife. Minus 10 is just fine if the wind is light. We generally use landplanes with skiis, but the killer set-up is flying boats -- they don't care about ruts in the snow.

I won our "first Flight" competition at our New Year's Day fun fly with a Seamaster 40 (TT 46 Pro). First prize was (note was) a 40oz bottle of Puerto Rican rum -- it was happily shared by all of the frozen pilots.