We dont get the cold winters you have (no snow) but mine prefer to sit outside on winter evenings than sit inside with the heater on. As for summer, if its over 35C they only get a 15min walk or we just sit in the shade at the oval. They really do feel the heat after a certain point. If the air is still they feel the heat more, and if there isn't much shade. I do find they will overheat themselves before they realise how hot they are. So I need to keep an eye on how much energy they expend on hot days and stop them running around.