Santa Rosa averages 26.2 days a year above 90°F, with December the wettest month at 6.47 in of normal rain. The hottest day on record was 115°F on Sep 6, 2022; the coldest, 16°F on Dec 9, 1972. The single biggest 24-hour rain event recorded was 7.83 in on Oct 24, 2021.
Climate and Average Weather Year Round in Santa Rosa
Year-round temperature
In Santa Rosa, the warmest months are June through September, with average daily highs between 80°F and 84°F. The coldest stretch runs December through February, with highs between 59°F and 64°F and overnight lows reaching 38°F.
Rainfall through the year
Rainfall in Santa Rosa averages 2.6 in per month over the long run. December is the wettest at 6.5 in, while July is the driest at 0.0 in.
Days at 90 °F or hotter
Santa Rosa averages 26.2 days per year at 90 °F or hotter. The hottest year on record saw 55 such days (2020); the coolest just 4 (2026).
Precipitation this year
As of May 29, Santa Rosa has received 14.6 in of precipitation this year — 25% below the long-term normal for this point in the year (19.6 in).