Montreal weather in September
September in Montreal: nice, rainy, with clean air — one of the best months to visit.
#2 of 12 months in Montreal · #139 of 604 destinations to visit in September · comfort 87/100 (tier A)
Updated June 2026 · climate normals from ERA5 reanalysis
Montreal climate normals — September
| Daytime high | 20°C / 67°F | 😎 nice |
|---|---|---|
| Nighttime low | 12°C / 54°F | |
| Feels like (high) | 19°C / 66°F | |
| Rainfall | 86 mm / 3.4 in | 🌧 rainy |
| Rainy days | 9 days | |
| Humidity | 77% | 💦 very humid |
| Dew point | 12°C / 53°F | |
| Sunshine | 9.1 h/day | |
| Daylight | 12.5 h | |
| Wind | 16 km/h / 10 mph | |
| Air quality (US AQI) | 47 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
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Montreal in September — FAQ
- Is September a good time to visit Montreal?
- September in Montreal: nice, rainy, with clean air — one of the best months to visit. It ranks #2 of 12 months for Montreal on SeasonMap's comfort score (87/100).
- What is the weather like in Montreal in September?
- In September, Montreal averages a daily high of 19.6°C and a low of 12°C, with about 86 mm of rain over roughly 9 rainy days.
- What is the air quality in Montreal in September?
- Montreal has a mean US Air Quality Index of about 47 in September.