In September, Saint-Jean-sur-Richelieu typically sees daytime highs of 20.1°C and overnight lows around 9.3°C. Compared to the annual average high of 11.2°C, September runs +8.9°C.
September in Saint-Jean-sur-Richelieu averages a daytime high of 20.1°C and an overnight low of 9.3°C.
September runs +8.9°C compared to Saint-Jean-sur-Richelieu's annual average high of 11.2°C, ranking #4 of 12 months by warmth.
Plan for daytime highs near 20.1°C and cooler evenings around 9.3°C.