Historical weather data, all-time temperature records, and monthly climate averages for Half Moon Bay, CA. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 5th in Half Moon Bay is a mild, mostly dry affair — 82 years of data put the average high at 59° and the low at 45°, with just a 23% chance of rain. The date has seen some swings, though: a balmy 74° in 2016 on one end, and a sharp 34° low back in 2009 on the other.
Half Moon Bay's coastal temperament keeps extremes relatively rare, but they do happen — the all-time high hit 94° on October 26, 2003, a reminder that fall can occasionally go rogue. On the cold side, a 19° reading on December 23, 1990 still stands as the benchmark, while a single December day in 2002 dumped 5.5 inches of rain.
Half Moon Bay is one of California's most temperature-stable spots — monthly average highs range only from 58° in early January to 67° in mid-September, a spread of less than 10 degrees all year. If you're chasing the warmest weather, aim for mid-September; if you want to avoid rain, skip late December, which averages 1.35 inches in its final week alone.