In September, St. Louis typically sees daytime highs of 27.5°C and overnight lows around 14.7°C. Compared to the annual average high of 19.0°C, September runs +8.5°C.
September in St. Louis averages a daytime high of 27.5°C and an overnight low of 14.7°C.
September runs +8.5°C compared to St. Louis's annual average high of 19.0°C, ranking #4 of 12 months by warmth.
Plan for daytime highs near 27.5°C and cooler evenings around 14.7°C.