Thousand Islands in May

May through October delivers the best weather, but timing depends on your priorities. June and July bring peak crowds and prices—hotel rooms in Alexandria Bay hit $200+ per night. But the weather's perfect and everything's open. September offers the sweet spot: smaller crowds, fall colors starting to show, and water still warm enough for swimming. October delivers spectacular foliage, especially on the Canadian side. May can be chilly with some attractions still closed, but you'll have the place mostly to yourself. Winter shuts down most boat tours, though ice fishing and snowmobiling take over. The river rarely freezes completely anymore due to shipping traffic, creating dramatic ice formations worth seeing if you don't mind the cold.