Historical weather data, all-time temperature records, and monthly climate averages for Santa Rosa, CA. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 5th in Santa Rosa typically lands in the mid-60s, with today's historical average sitting at a pleasant 68° high and 42° low. There's about a 1-in-4 chance of rain, though the date has seen some wild swings — 90° in 1939 and a hard freeze down to 29° back in 1918.
Santa Rosa plays in extremes: the all-time high hit a blistering 115° on September 6, 2022, while the coldest ever recorded was 9° on Christmas Day 1924. The wettest single day on record dumped 7.83 inches on October 24, 2021 — a reminder that Northern California's dry summers give way to some serious atmospheric rivers.
Santa Rosa runs warm and dry from late spring through early fall, peaking around 83–84° in late August and early September before cooling into the rainy season. January is the coolest month, averaging just 58° for a high, and late December is the wettest stretch of the year. If you're chasing sun, aim for July through September; if you want to avoid the rain, skip December through February.