July in Longueuil averages a daily high of 26.5°C with nights around 17.7°C. Expect roughly 11.6 wet days totalling 102.1mm. 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 July data.