Historical weather data, all-time temperature records, and monthly climate averages for Hillsborough, CA. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 5 in Hillsborough lands right in the mild middle — expect a high near 63° and a low around 48°. There's a one-in-four chance of rain, so don't put the umbrella away just yet. The date has seen everything from a balmy 84° back in 1989 to a chilly 39° low in 1975.
Hillsborough's weather has a wider range than its manicured streets might suggest — temperatures have swung from a frozen 24° in December 1972 all the way up to 105° in June 2000. The wettest single day on record dumped 5.59 inches on January 4, 1982, and the town even saw 1.5 inches of snow on January 21, 1962.
Hillsborough is warmest in early September, when average highs reach 74°, and coolest in early January at just 55°. The temperature range is remarkably narrow year-round — a classic Bay Area marine climate with mild summers and gentle winters. If you want to dodge the rain, avoid late December, which is the wettest stretch of the year at over an inch of precipitation per week.