In September, Vallejo typically sees daytime highs of 26.7°C and overnight lows around 11.5°C. Compared to the annual average high of 20.8°C, September runs +5.9°C.
September in Vallejo averages a daytime high of 26.7°C and an overnight low of 11.5°C.
September runs +5.9°C compared to Vallejo's annual average high of 20.8°C, ranking #3 of 12 months by warmth.
Plan for daytime highs near 26.7°C and cooler evenings around 11.5°C.