San Bruno experiences mild winters with occasional cold snaps, as evident in the low temperatures ranging from -2°C to 27°C in January and December. As spring approaches, temperatures gradually rise, with April averaging around 13°C, marking a gentle warming trend. Summer months bring warmth, with July being the hottest, but even then temperatures rarely exceed 41°C. Autumn sees a return to milder conditions, with October experiencing temperatures similar to those of late spring. Winters are generally cool and wet, while springs and autumns offer pleasant weather.