There are very few days in an Ontario summer when the temperature would be any less than 22-25C and sometimes it can reach into the 30's for days at a time. Air conditioning is standard fare in most business buildings and very common in homes, The coastal Provinces would not experience it quite so warm, but good warm summers are normal. The Prairie Provinces (Manitoba/Saskatchewan) have very warm, dry summers. All-in-all Summers in Canada are far better than in the UK.