South San Francisco experiences mild winters, with temperatures ranging from around freezing to the mid-20s Celsius. Spring brings gradual warming, with temperatures rising to the late 30s by April and May. Summer months are warm to hot, with highs often reaching above 40 degrees Celsius in June and July. Autumn sees a decline in temperature, with cooler nights returning by October, though highs can still reach into the mid-30s. Winters are generally cool, with temperatures dipping below zero on occasion, but rarely staying low for extended periods.