In August, Castro Valley typically sees daytime highs of 25.5°C and overnight lows around 13.3°C. Compared to the annual average high of 20.0°C, August runs +5.5°C.
August in Castro Valley averages a daytime high of 25.5°C and an overnight low of 13.3°C.
August runs +5.5°C compared to Castro Valley's annual average high of 20.0°C, ranking #3 of 12 months by warmth.
Plan for daytime highs near 25.5°C and cooler evenings around 13.3°C.