September in Sioux Falls averages a daily high of 24.3°C with nights around 11°C. Expect roughly 8 wet days totalling 64.6mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Sioux Falls is August–September.
Based on SIOUX FALLS FOSS FIELD, SD US (4.9km), 1995–2024. 30 years of September data.