Well, ..., it should be absolutely fine. What can be affected more is the grease in your focuser or in the gears of it's mechanism. I actually use a Teflon based grease that resists cold weather very well.
Over all you will get your best image when your scope reaches thermal equilibrium (same temperature as the surrounding environment) with the outside. Until, that time stars in the scope will appear to be "Blobby" and "Boily" in appearance. So an imbalance in temperature will affect the quality of your image. However, once the scope reaches thermal equilibrium stars will "Snap" right into focus and (provided that your collimation is right) resolve to fine pinpoints of light. Objects such a Jupiter will be crisply defined and cloud banding (depending on aperture size) on the planet should be readily apparent.
-EDIT- I should note that I do a lot of cold weather observing (well maybe not as cold as those in Canada but well below freezing for sure) and it doesn't affect my scope. You, however, may want to get some decent cold weather gear Like 'wearguard' coveralls, Boots with thinsulate soles, good gloves that allow your fingers to stay nimble and dexterous yet warm and a warm hat with ear coverings. I do some of my best of serving when the night is clear, dry, and below freezing.