Ontario Temperature Ranges by Season and Region

Summer (Jun–Aug)

• South (Toronto, Windsor): 20–30°C (68–86°F); heat waves >35°C (95°F)
• North (Timmins, Thunder Bay): 15–25°C (59–77°F); cooler nights

Winter (Dec–Feb)

• South: -5 to -15°C (23 to 5°F); cold snaps < -25°C (-13°F)
• North: -15 to -30°C (5 to -22°F); extreme < -40°C (-40°F)
• Lake effect: Snowbelts (Barrie, London, Owen Sound) get heavy snow

Spring (Mar–May) & Fall (Sep–Nov)

• Variable: -5 to 20°C (23–68°F). Late frost risk into May. Fall color peak late Sep–Oct.

Microclimates

• Niagara Peninsula: Milder (fruit/wine)
• Ottawa Valley: Colder winters, hotter summers
• Great Lakes shores: Lake-effect snow, moderated temps

Always check Environment Canada or WeatherCAN app for local forecasts.