Historical weather data, all-time temperature records, and monthly climate averages for Mill Valley, CA. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 5th in Mill Valley runs mild, with 124 years of data pointing to an average high of 67° and a low of 44°. There's a 29% chance of rain — not unlikely, but not a sure thing either. The date has seen wild swings, from a scorching 88° in 1924 down to a hard freeze at 31° back in 1918.
Mill Valley plays it warm for a Bay Area town, but it's not without teeth — temperatures have swung from a brutal 112° in July 1913 all the way down to 17° on New Year's Eve 1915. Rain is where things get dramatic: a single January day in 1967 dropped 11.56 inches, which remains the all-time record. Snow is essentially a myth here, with a lone inch on Christmas Day 1948 standing as the high-water mark.
Summer is the move for warmth, with mid-July averaging highs around 84° and the heat holding strong through September. If you're cold-averse, skip January — highs hover in the mid-50s and the last week of December is the wettest of the year, averaging over 2.5 inches. Spring arrives fast here, with April already nudging 69°, making it a sweet spot before summer crowds.