September in Deventer averages a daily high of 19.6°C with nights around 9.6°C. Expect roughly 12.1 wet days totalling 61.9mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Deventer is May–September.
Based on HEINO, NL (20.9km), 1995–2024. 29 years of September data.