December in Sioux Falls averages a daily high of -0.4°C with nights around -10.5°C. Expect roughly 7 wet days totalling 25.3mm. A hard month to visit for comfort alone.
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 December data.