August in Great Falls averages a daily high of 29°C with nights around 11.8°C. Expect roughly 6.2 wet days totalling 35mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Great Falls is August–September.
Based on GREAT FALLS 16ST, MT US (2.1km), 1995–2024. 15 years of August data.