I dont think we've had a normal winter in YYZ for 2 years maybe 3. One day its -12c, the next +8c. Very odd weather indeed. In the summer we can and often do hit +30-35c and +40-45c with the humidex. IIRC this past summer was the worst for smog days. That being said I woudlnt move for anything. YYZ is a great city with loads to do and see.