In December, San Mateo typically sees daytime highs of 28.7°C and overnight lows around 17.1°C. Compared to the annual average high of 29.6°C, December runs -0.9°C.
December in San Mateo averages a daytime high of 28.7°C and an overnight low of 17.1°C.
December runs -0.9°C compared to San Mateo's annual average high of 29.6°C, ranking #12 of 12 months by warmth.
Plan for daytime highs near 28.7°C and cooler evenings around 17.1°C.