In September, Santa Rosa typically sees daytime highs of 20.5°C and overnight lows around 4.9°C. Compared to the annual average high of 23.4°C, September runs -2.8°C.
September in Santa Rosa averages a daytime high of 20.5°C and an overnight low of 4.9°C.
September runs -2.8°C compared to Santa Rosa's annual average high of 23.4°C, ranking #8 of 12 months by warmth.
Plan for daytime highs near 20.5°C and cooler evenings around 4.9°C.