September in Belleville averages a daily high of 22.5°C with nights around 12.3°C. Expect roughly 10 wet days totalling 87.9mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Belleville is May–September.
Based on BELLEVILLE, ON CA (2.3km), 1995–2024. 27 years of September data.