In September, Thunder Bay typically sees daytime highs of 16.2°C and overnight lows around 5.3°C. Compared to the annual average high of 8.0°C, September runs +8.2°C.
September in Thunder Bay averages a daytime high of 16.2°C and an overnight low of 5.3°C.
September runs +8.2°C compared to Thunder Bay's annual average high of 8.0°C, ranking #4 of 12 months by warmth.
Plan for daytime highs near 16.2°C and cooler evenings around 5.3°C.