August in Duluth averages a daily high of 23.9°C with nights around 14.7°C. Expect roughly 9.3 wet days totalling 95.2mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Duluth is June–September.
Based on SUPERIOR, WI US (6.8km), 1995–2024. 29 years of August data.