In September, Montreal typically sees daytime highs of 19.8°C and overnight lows around 9.2°C. Compared to the annual average high of 10.8°C, September runs +9.0°C.
September in Montreal averages a daytime high of 19.8°C and an overnight low of 9.2°C.
September runs +9.0°C compared to Montreal's annual average high of 10.8°C, ranking #4 of 12 months by warmth.
Plan for daytime highs near 19.8°C and cooler evenings around 9.2°C.