In September, Riverside typically sees daytime highs of 32.4°C and overnight lows around 14.7°C. Compared to the annual average high of 25.7°C, September runs +6.7°C.
September in Riverside averages a daytime high of 32.4°C and an overnight low of 14.7°C.
September runs +6.7°C compared to Riverside's annual average high of 25.7°C, ranking #3 of 12 months by warmth.
Plan for daytime highs near 32.4°C and cooler evenings around 14.7°C.