Picture choosen by: Mr.David Birch Climate of Canada It is common to have summer thunderstorms throughout Canada, and occasionally these may become severe. Tornados also occur throughout Canada, with May to September being the prime months. The peak season is June and early July in southern Ontario, Alberta, southeastern Quebec, and a band stretching from southern Saskatchewan and Manitoba, through the Thunder Bay. The interior of British Columbia and western New Brunswick are also tornado zones. Earth tremors occur in western mountains while forest fires can occur at any time regardless of season, and particularly in the grasslands and forests of western Canada.