August in St. Louis averages a daily high of 31.4°C with nights around 21.1°C. Expect roughly 7.4 wet days totalling 96.2mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit St. Louis is April–May.
Based on ST LOUIS SCIENCE CENTER, MO US (6.3km), 1995–2024. 20 years of August data.