September in Rennes averages a daily high of 22.2°C with nights around 11.5°C. Expect roughly 9.6 wet days totalling 49.1mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Rennes is May–September.
Based on RENNES ST JACQUES, FR (6.4km), 1995–2024. 30 years of September data.