August in Sioux Falls averages a daily high of 27.9°C with nights around 16°C. Expect roughly 9.2 wet days totalling 91.1mm. 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 August data.