May in Duluth averages a daily high of 14°C with nights around 5°C. Expect roughly 11.2 wet days totalling 79.4mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Duluth is June–September.
Based on SUPERIOR, WI US (6.8km), 1995–2024. 30 years of May data.