August in Belleville averages a daily high of 26.5°C with nights around 16.4°C. Expect roughly 9.8 wet days totalling 73mm. 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 August data.