In September, Petaluma typically sees daytime highs of 23.6°C and overnight lows around 11.1°C. Compared to the annual average high of 18.5°C, September runs +5.1°C.
September in Petaluma averages a daytime high of 23.6°C and an overnight low of 11.1°C.
September runs +5.1°C compared to Petaluma's annual average high of 18.5°C, ranking #1 of 12 months by warmth.
Plan for daytime highs near 23.6°C and cooler evenings around 11.1°C.