In September, Siedlce typically sees daytime highs of 18.3°C and overnight lows around 7.7°C. Compared to the annual average high of 11.5°C, September runs +6.7°C.
September in Siedlce averages a daytime high of 18.3°C and an overnight low of 7.7°C.
September runs +6.7°C compared to Siedlce's annual average high of 11.5°C, ranking #4 of 12 months by warmth.
Plan for daytime highs near 18.3°C and cooler evenings around 7.7°C.