Ottawa weather in August
August in Ottawa: warm, rainy, with clean air — an excellent time to visit.
#3 of 12 months in Ottawa · #273 of 897 destinations to visit in August · comfort 87/100 (tier A)
Updated June 2026 · climate normals from ERA5 reanalysis
Traveller notes on Ottawa in August
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Ottawa climate normals — August
| Daytime high | 25°C / 77°F | 🌤 warm |
|---|---|---|
| Nighttime low | 17°C / 62°F | |
| Rainfall | 94 mm / 3.7 in | 🌧 rainy |
| Rainy days | 14 days | |
| Humidity | 77% | 💦 very humid |
| Dew point | 16°C / 60°F | |
| Sunshine | 10.5 h/day | |
| Daylight | 14.1 h | |
| Wind | 13 km/h / 8 mph | |
| Air quality (US AQI) | 40 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
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Ottawa in August — FAQ
- Is August a good time to visit Ottawa?
- August in Ottawa: warm, rainy, with clean air — an excellent time to visit. It ranks #3 of 12 months for Ottawa on SeasonMap's comfort score (87/100).
- What is the weather like in Ottawa in August?
- In August, Ottawa averages a daily high of 25.1°C and a low of 16.7°C, with about 93.7 mm of rain over roughly 14 rainy days.
- What is the air quality in Ottawa in August?
- Ottawa has a mean US Air Quality Index of about 40 in August.