September in Saint Joseph averages a daily high of 27.2°C with nights around 13°C. Expect roughly 8.3 wet days totalling 72.1mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Saint Joseph is April–May.
Based on ST JOSEPH ROSECRANS MEMORIAL AIRPORT, MO US (5.4km), 1995–2024. 27 years of September data.