September in Koblenz averages a daily high of 19.8°C with nights around 8.8°C. Expect roughly 9.8 wet days totalling 52.9mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Koblenz is June–September.
Based on MONTABAUR, GM (18.7km), 1995–2024. 17 years of September data.