In May, San Mateo typically sees daytime highs of 18.5°C and overnight lows around 9.3°C. Compared to the annual average high of 17.7°C, May runs +0.8°C.
May in San Mateo averages a daytime high of 18.5°C and an overnight low of 9.3°C.
May runs +0.8°C compared to San Mateo's annual average high of 17.7°C, ranking #6 of 12 months by warmth.
Plan for daytime highs near 18.5°C and cooler evenings around 9.3°C.