In September, Simi Valley typically sees daytime highs of 28.2°C and overnight lows around 14.3°C. Compared to the annual average high of 22.3°C, September runs +5.9°C.
September in Simi Valley averages a daytime high of 28.2°C and an overnight low of 14.3°C.
September runs +5.9°C compared to Simi Valley's annual average high of 22.3°C, ranking #3 of 12 months by warmth.
Plan for daytime highs near 28.2°C and cooler evenings around 14.3°C.