The best time to visit Longueuil is during the summer months, from June to August, or in early autumn, particularly September, for pleasant weather and a full calendar of activities.Summer in Longueuil offers warm temperatures, ideal for enjoying outdoor attractions and exploring the city's parks. You'll find many local festivals and events taking place, making it a lively time to visit. It's great for families looking to make the most of the long daylight hours and outdoor pursuits.Early autumn, especially September, is also an excellent time to visit. The weather remains mild and comfortable, and the changing leaves provide a beautiful backdrop for walks and sightseeing.