Ontario climate
World Climates covers 16 places in Ontario. By annual mean temperature, the warmest is St. Catharines (10 °C50 °F) and the coolest is Thunder Bay (4 °C40 °F). The wettest is Ottawa with 981 mm39 in of precipitation per year, the driest Barrie with 623 mm25 in.
The most common climate types (Köppen classification computed from these averages) are warm-summer humid continental (Dfb, 8 places) and hot-summer humid continental (Dfa, 8 places).
The highest monthly average high is in Brampton (29 °C84 °F in July); the lowest monthly average low is in Greater Sudbury (−18 °C0 °F in January).
Across the places in Ontario, the months that most often rank as the most comfortable are June, August and September (16, 16 and 16 of 16 places respectively).
Frequently asked questions
Which is the warmest place in Ontario?
By annual mean temperature, the warmest place in Ontario is St. Catharines at 10 °C50 °F. The coolest is Thunder Bay at 4 °C40 °F.
Where does it rain the most in Ontario?
Ottawa gets the most precipitation, 981 mm39 in in an average year. The driest place is Barrie with 623 mm25 in.
How many places in Ontario does this site cover?
World Climates has climate data for 16 places in Ontario. Each one has a page with monthly averages for temperature, rainfall, humidity and daylight.
When is the best time to visit Ontario?
It depends on the place. Across Ontario, the months that most often rank as the most comfortable are June, August and September. Check the page of each city for its own best months.
Climate of every place in Ontario
| Place | Year | Max high | Min low | Precip. |
|---|---|---|---|---|
| Toronto | 9 | 25 | −6 | 774 |
| Ottawa | 6 | 26 | −16 | 981 |
| Brampton | 8 | 29 | −10 | 770 |
| London | 9 | 28 | −8 | 660 |
| Markham | 8 | 28 | −10 | 723 |
| Kitchener | 8 | 28 | −10 | 762 |
| Windsor | 9 | 28 | −8 | 848 |
| Oshawa | 9 | 28 | −9 | 719 |
| Greater Sudbury | 4 | 25 | −18 | 817 |
| Barrie | 7 | 26 | −10 | 623 |
| Guelph | 8 | 28 | −11 | 770 |
| St. Catharines | 10 | 27 | −6 | 872 |
| Kingston | 9 | 24 | −7 | 942 |
| Ajax | 9 | 28 | −9 | 719 |
| Thunder Bay | 4 | 25 | −17 | 632 |
| Brantford | 9 | 28 | −8 | 791 |
Year = annual mean temperature; max high = average high of the warmest month; min low = average low of the coldest month; precip. = annual total. Temperatures in °C°F, precipitation in mminches. Sorted by population.
Other cities over 100,000 people
These cities share a NASA POWER grid cell with a larger place, so their averages are shown on that page:
- Mississauga → data of Toronto
- Detroit → data of Windsor
- Hamilton → data of Brampton
- Etobicoke → data of Toronto
- Vaughan → data of Markham
- Gatineau → data of Ottawa
- Oakville → data of Toronto
- Richmond Hill → data of Markham
- Burlington → data of Brampton
- Nepean → data of Ottawa
- Gloucester → data of Ottawa
- Whitby → data of Oshawa
- Warren → data of Windsor
- Milton → data of Brampton
- Sterling Heights → data of Windsor
- Cambridge → data of Kitchener
- Orléans → data of Ottawa
- Ottawa South → data of Ottawa
- Thornhill → data of Markham
- Waterloo → data of Kitchener
Data: NASA POWER climatology 2001–2025 (MERRA-2 reanalysis, CERES satellite data) — grid-cell averages, not station records. Sources and method.