In September, Bismarck typically sees daytime highs of 21.9°C and overnight lows around 6.3°C. Compared to the annual average high of 11.9°C, September runs +10.0°C.
September in Bismarck averages a daytime high of 21.9°C and an overnight low of 6.3°C.
September runs +10.0°C compared to Bismarck's annual average high of 11.9°C, ranking #4 of 12 months by warmth.
Plan for daytime highs near 21.9°C and cooler evenings around 6.3°C.