March in St. Louis averages a daily high of 13.6°C with nights around 3.4°C. Expect roughly 9.9 wet days totalling 97.2mm. 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. 21 years of March data.