Montreal Weather in September
In September, Montreal averages a high of 20°C (69°F) and a low of 12°C (54°F), from 54 years of daily records (1971–2026).
20°C
Average high
69°F
12°C
Average low
54°F
33°C
Record high
92°F · September 9, 2002
-2°C
Record low
28°F · September 29, 1995
What September Is Like in Montreal
- September in Montreal has become 1.8°C (3.2°F) warmer on average: the 2011–2025 average against 1970–1989.
- 6 of the 10 warmest Septembers on record in Montreal have come since 2011.
- The coldest September reading, -2°C (28°F) on September 29, 1995, has not been matched in 31 years.
- The warmest September in the record was 2015; the coldest was 1995.
At least 1 mm of rain falls on 32% of September days, and the month averages 94 mm in total.
Warmest: 2015 (24.1°C)Latest: 2025 (22.5°C)10-year averageLong-run average (20.4°C)
Look Up a Day in September
See the weather in Montreal on any September date, year by year.
Source: NOAA GHCN-Daily, Mctavish (1994–2026); Montreal Mcgill (1971–1993); Montreal/St-Hubert A (1979–2009). Averages cover 1971–2026. How we compute this