Santa Rosa weather in August
In August, Santa Rosa has daytime highs averaging 30 °C, nights around 14 °C, with 0.2 wet days. Figures are 1991–2020 climate normals.
- 29.9°C Average high
- 14.2°C Average low
- 0.2days Wet days
- 1mm Rainfall
- 14h Daylight
Daily temperatures through August
How August develops
Averages for the first, middle and last part of the month, from daily 1991–2020 normals. Chance of rain is the share of years in which that calendar day recorded more than 1 mm.
| Days | Avg high | Avg low | Chance of rain |
|---|---|---|---|
| 1–10 August | 29.7 °C | 14.1 °C | 0 % |
| 11–20 August | 30.2 °C | 14.3 °C | 0 % |
| 21–31 August | 29.8 °C | 14.3 °C | 1 % |
What to expect
| Measure | Typical August | Share of the month |
|---|---|---|
| Days above 25 °C | 29 of 31 | 92 % |
| Days above 30 °C | 14 of 31 | 46 % |
| Days below 0 °C | 0 of 31 | 0 % |
| Days with more than 1 mm rain | 0.2 of 31 | 1 % |
Conditions in August
| Measure | Average |
|---|---|
| Mean temperature | 21 °C |
| Record high (1991–2020) | 41 °C |
| Record low (1991–2020) | 11 °C |
| Relative humidity | 62 % |
| Wind speed | 13 km/h |
| Cloud cover | 17 % |
Where Santa Rosa ranks in August
| Ranking | Position | Value |
|---|---|---|
| The driest places in North America in August | 21stof 50 | 1.1 mm |
August compared with the months around it
| Month | Avg high | Rainfall | Cloud |
|---|---|---|---|
| June | 28.3 °C | 7 mm | 25 % |
| July | 29.9 °C | under 1 mm | 16 % |
| August | 29.9 °C | 1 mm | 17 % |
| September | 28.9 °C | 3 mm | 19 % |
| October | 24.9 °C | 33 mm | 33 % |
See all twelve months for Santa Rosa
- August is the 2nd warmest month here.
- It is the 2nd driest month of the year.
- It ranks 2nd for least cloud cover.
- Days last about 14 hours from sunrise to sunset.
- It rains on 0.2 of 31 days — 1 % of the month.
- Nights are about 16 °C cooler than the middle of the day.
- The hottest August day on record since 1991 reached 41 °C, 12 °C above the usual daytime high.
Nearby destinations in August
| Destination | Avg high | Wet days | Sea |
|---|---|---|---|
| Santa Rosa | 30 °C | 0.2 | – |
| San Francisco | 22 °C | 0 | 14 |
| Oakland | 26 °C | 0 | – |
QuestionsAugust in Santa Rosa, answered
How warm is Santa Rosa in August?
Daily highs average 30 °C and nights fall to about 14 °C, a spread of 16 °C between afternoon and dawn. That makes August the 2nd warmest month of the year here.
Does it rain much in Santa Rosa in August?
August averages 1 mm of rain, spread over about 0 of the 31 days — 1 % of the month. Cloud cover averages 17 % of the sky.
How long are the days in August?
Santa Rosa averages 14 hours between sunrise and sunset in August. Day length is computed from latitude and date, so it is exact rather than modelled — but it says nothing about how much of that time is sunny.
Data sources and method
- ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
- Open-Meteo — Open-Meteo.com. CC BY 4.0
- NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
- GeoNames — GeoNames.org. CC BY 4.0
- Normal period
- 1991–2020
- Dataset version
- era5-1991-2020-scores1.1
- Last processed
Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: daylight hours, beach and comfort scores, monthly rankings, threshold day counts, chance of a wet day by date, ten-day averages within the month. Full formulas are on the methodology page.
Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.