Santa Rosa (CA) Temperature by Month

The average annual maximum temperature in Santa Rosa, California, United States of America is 22°C (72°F), with daytime highs ranging from 14°C (57°F) in December to 28°C (82°F) in September. This page covers monthly averages, day-night differences, and how Santa Rosa compares to cities worldwide.

The weather in Santa Rosa experiences significant differences between warm and cold seasons, with big shifts in temperature. At night, minimum temperatures range from 11°C (52°F) in September to 4°C (39°F) in December.

The chart below illustrates the average maximum day and minimum night temperatures in Santa Rosa by month:

The minimum temperature is often recorded between 4 AM and 6 AM, while the highest temperature is usually reached at 3 PM, when the sun's heating effect is strongest. September, the warmest month, gets 275 hours of sunshine.

The chart below shows the average temperature throughout the year:

Santa Rosa's average annual maximum temperature is 22°C (72°F). To put that in context, here's how it compares to a few well-known destinations:

Barcelona, Spain has an annual average of around 21°C (70°F), with warm summers and mild, fairly short winters.

Queenstown, New Zealand averages 10°C (50°F) annually, remember seasons are flipped, so its coldest months fall in June and July.

Buenos Aires, Argentina averages 23°C (73°F) a year, with hot summers and mild winters, and seasons reversed compared to Europe.

Tokyo, Japan averages 21°C (70°F) a year, with hot summers, cool winters, and a well-defined cherry blossom spring.

Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.

The readings come from a range of sources, land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.

Seasonal temperature shifts influence more than just how warm it feels, they also drive changes in rainfall, cloud cover, and wind patterns throughout the year.

Warmer air holds more moisture, which tends to mean heavier or more frequent rain during the warmer months. When temperatures drop in winter, any precipitation that does fall is more likely to come as snow or sleet, though in Santa Rosa this rarely lasts long on the ground.

For more on Santa Rosa's weather, including monthly rainfall, sunshine hours, and humidity, visit our Santa Rosa climate page.