Ontario weather in August
August is one of the best months to visit Ontario: highs of 25°C (76°F) and about 59 mm (2.3 in) of rain on average. Nights average 19°C (65°F) and cloud cover 62% (NASA POWER, 2001–2025 averages). It is the 4th driest month of the year and the 2nd warmest. Compared with July, it is about as warm and drier; September brings highs of 21°C (70°F) and 66 mm (2.6 in) of rain.
Figures are long-term averages for Toronto, the largest city in Ontario. See below for other places.
Is August a good time to visit Ontario?
best month Weather score 78/100.
Yes. August is one of the best months for weather in Ontario.
Does it rain a lot in Ontario in August?
No, it is usually dry: about 59 mm (2.3 in) falls in an average August. It is the 4th driest month of the year.
How warm is Ontario in August?
Days average 25°C (76°F) and nights 19°C (65°F).
Ontario weather by month
| Month | High | Low | Rain | Cloud | Weather |
|---|---|---|---|---|---|
| January | 0°C (31°F) | -5°C (23°F) | 54 mm | 81% | least pleasant |
| February | 0°C (32°F) | -5°C (22°F) | 49 mm | 79% | least pleasant |
| March | 4°C (38°F) | -2°C (28°F) | 53 mm | 74% | least pleasant |
| April | 9°C (48°F) | 2°C (36°F) | 71 mm | 75% | least pleasant |
| May | 15°C (59°F) | 8°C (46°F) | 73 mm | 74% | fair |
| June | 21°C (70°F) | 14°C (58°F) | 71 mm | 68% | best |
| July | 25°C (77°F) | 18°C (65°F) | 75 mm | 64% | best |
| August | 25°C (76°F) | 19°C (65°F) | 59 mm | 62% | best |
| September | 21°C (70°F) | 15°C (60°F) | 66 mm | 60% | best |
| October | 14°C (57°F) | 9°C (48°F) | 74 mm | 74% | fair |
| November | 8°C (46°F) | 3°C (37°F) | 66 mm | 75% | least pleasant |
| December | 3°C (37°F) | -2°C (29°F) | 63 mm | 81% | least pleasant |
Sources: 2001–2025 monthly averages from NASA POWER (MERRA-2 reanalysis). Page updated . How we rate months
Weather across Ontario in August
Weather can differ a lot within Ontario: coasts, hills and mountains each have their own climate.
| Place | High | Low | Rain | Weather |
|---|---|---|---|---|
| Toronto | 25°C (76°F) | 19°C (65°F) | 59 mm | best |
| Ottawa | 25°C (77°F) | 14°C (58°F) | 88 mm | best |
| Mississauga | 25°C (76°F) | 19°C (65°F) | 59 mm | best |
| Brampton | 28°C (82°F) | 15°C (60°F) | 63 mm | best |
| Hamilton | 28°C (82°F) | 15°C (60°F) | 63 mm | best |
| London | 27°C (81°F) | 16°C (61°F) | 55 mm | best |
| Etobicoke | 25°C (76°F) | 19°C (65°F) | 59 mm | best |
| Markham | 27°C (80°F) | 16°C (61°F) | 55 mm | best |
| Vaughan | 27°C (80°F) | 16°C (61°F) | 55 mm | best |
| Kitchener | 27°C (80°F) | 15°C (58°F) | 63 mm | best |
| Windsor | 27°C (81°F) | 17°C (62°F) | 82 mm | best |
| Oakville | 25°C (76°F) | 19°C (65°F) | 59 mm | best |