September in Dubuque averages a daily high of 24.3°C with nights around 13°C. Expect roughly 8 wet days totalling 89.1mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Dubuque is August–September.
Based on DUBUQUE LOCK AND DAM 11, IA US (4.6km), 1995–2024. 30 years of September data.