In January, Castro Valley typically sees daytime highs of 12.8°C and overnight lows around 4.9°C. Compared to the annual average high of 20.0°C, January runs -7.2°C.
January in Castro Valley averages a daytime high of 12.8°C and an overnight low of 4.9°C.
January runs -7.2°C compared to Castro Valley's annual average high of 20.0°C, ranking #12 of 12 months by warmth.
Plan for daytime highs near 12.8°C and cooler evenings around 4.9°C.