October in Longueuil averages a daily high of 13.6°C with nights around 6.2°C. Expect roughly 11.8 wet days totalling 112.3mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Longueuil is May–September.
Based on MCTAVISH, QC CA (9.1km), 1995–2024. 28 years of October data.