September in Siedlce averages a daily high of 19.1°C with nights around 8.3°C. Expect roughly 10 wet days totalling 48.1mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Siedlce is May–September.
Based on SIEDLCE, PL (9.5km), 1995–2024. 30 years of September data.