In September, Saint John typically sees daytime highs of 18.3°C and overnight lows around 8.0°C. Compared to the annual average high of 10.4°C, September runs +7.9°C.
September in Saint John averages a daytime high of 18.3°C and an overnight low of 8.0°C.
September runs +7.9°C compared to Saint John's annual average high of 10.4°C, ranking #4 of 12 months by warmth.
Plan for daytime highs near 18.3°C and cooler evenings around 8.0°C.