September in Troisdorf averages a daily high of 20.7°C with nights around 9.8°C. Expect roughly 12.1 wet days totalling 66.2mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Troisdorf is May–September.
Based on KOLN BONN, GM (6.3km), 1995–2024. 30 years of September data.