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Live forecasts update automatically; written guidance last reviewed 16 June 2026 by the Canada Scope Weather Desk. Data from Environment and Climate Change Canada and other national met services via Open-Meteo.
Check the forecast for your region before heading out, because Ontario’s weather varies sharply from the Great Lakes shoreline to the northern boreal forest. The province’s climate is continental, meaning hot, humid summers and cold, snowy winters, with lake-effect snow a frequent factor near Lake Ontario and Lake Erie.
What drives Ontario’s weather patterns?
Ontario’s weather is shaped by two main forces: latitude and the Great Lakes. Southern Ontario, including the Greater Toronto Area, experiences milder winters and more thunderstorms in summer due to lake moderation. Northern Ontario sees longer, colder winters and shorter summers, with the Canada weather hub showing a typical January high of -10°C in Thunder Bay versus -1°C in Windsor. The ontario weather map often reveals a sharp temperature gradient between these zones, especially during cold-air outbreaks.
What should you expect day to day?
For ontario weather tomorrow, expect lake-breeze fronts near the shoreline and possible lake-effect snow squalls from November through March. In summer, humidity can push the humidex above 40°C in cities like Toronto and London. For planning further ahead, weather in ontario 10 days and ontario weather 14 day forecasts are reliable for general trends but less so for precise precipitation timing. Hourly details, such as ontario weather hourly data, are best used within 48 hours. Long-range outlooks, like an ontario weather forecast 30 days, indicate broad patterns (e.g., warmer or drier than average) rather than exact conditions.
Does Ontario get tornadoes?
Yes, southern Ontario sees about 10 to 15 tornadoes per year, mostly in June and July. They are usually weak (EF0–EF2), but severe storms can produce damaging winds and hail. Always monitor weather warnings during thunderstorm season.
How accurate are 14-day forecasts for Ontario?
They are useful for spotting broad trends—like a warm spell or a cold front—but day-to-day accuracy drops sharply after 7 days. For reliable planning, check the ontario weather 14 day outlook and then confirm with the 48-hour forecast closer to the date.
What is lake-effect snow and where does it hit hardest?
Cold air passes over the relatively warm Great Lakes, picking up moisture that falls as heavy snow downwind. The snowbelts east of Lake Huron and Lake Ontario—including areas near London, Barrie, and Kingston—can see 200–300 cm of snow each winter. Check London Ontario weather for local details.