August in Longueuil averages a daily high of 25.6°C with nights around 16.9°C. Expect roughly 10.4 wet days totalling 106.3mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Longueuil is May–September.
Based on MCTAVISH, QC CA (9.1km), 1995–2024. 27 years of August data.