My friends tell me the perfect winter temperature is –4°C. "It's winter," they say, "it's going to be cold and you just have to get over it." What you don't want is cold and wet, and –4° they claim is the best temperature for dry cold. I must agree, I find the temperatures very good this year so far. They've been staying between 0° and –5°, and it feels great.
Check out this picture of the slow sliding off our roof. It's hanging down over the roof edge like a table cloth. It looks cool, but it's a sign of poor insulation in the roof.