In September, Olsztyn typically sees daytime highs of 17.7°C and overnight lows around 7.7°C. Compared to the annual average high of 11.0°C, September runs +6.7°C.
September in Olsztyn averages a daytime high of 17.7°C and an overnight low of 7.7°C.
September runs +6.7°C compared to Olsztyn's annual average high of 11.0°C, ranking #4 of 12 months by warmth.
Plan for daytime highs near 17.7°C and cooler evenings around 7.7°C.