In September, St. John's typically sees daytime highs of 16.3°C and overnight lows around 8.3°C. Compared to the annual average high of 9.1°C, September runs +7.2°C.
September in St. John's averages a daytime high of 16.3°C and an overnight low of 8.3°C.
September runs +7.2°C compared to St. John's's annual average high of 9.1°C, ranking #3 of 12 months by warmth.
Plan for daytime highs near 16.3°C and cooler evenings around 8.3°C.