Santa Rosa weather in September: Santa Rosa, California: normal highs, lows, rain and records for September
Santa Rosa in September has a normal high of 83°F and a normal low of 50°F, a daily mean of 67°F, falling from 85°F on the 1st to 81°F by the 30th. Measurable precipitation falls on 2 days in a normal September, 0.13 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 29°C and low of 10°C, 3 mm of precipitation in September.
- NOAA stationSanta Rosa Sonoma County Airport
- Station IDUSW00023213
- Location38.50°N 122.81°W
- Elevation114 ft (35 m)
- Population177,524
- Jan 58° 38°
- Feb 62° 39°
- Mar 65° 41°
- Apr 69° 43°
- May 75° 47°
- Jun 82° 50°
- Jul 84° 52°
- Aug 84° 52°
- Sep 83° 50°
- Oct 77° 46°
- Nov 65° 40°
- Dec 58° 37°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is Santa Rosa in September?
The normal high is 83°F and the normal low 50°F, for a daily mean of 66.5°F. September is 1.5°F cooler than August and 5.2°F warmer than October. September is the 3rd warmest month of the year in Santa Rosa and the 10th wettest. Across the month the normal high falls 4°F, from 85°F on September 1 to 81°F on September 30. From one year to the next September's mean temperature typically moves about 1.7°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 65°F and 68°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 9%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 85°F | 51°F | 3% | 1% |
| September 8 | 84°F | 50°F | 4% | 1% |
| September 15 | 84°F | 50°F | 6% | 2% |
| September 22 | 83°F | 49°F | 7% | 3% |
| September 30 | 81°F | 48°F | 9% | 4% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 1, coldest night September 30)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 85°F | 51°F | 3% | 1% | 13 h |
| September 2 | 85°F | 51°F | 3% | 1% | 13 h |
| September 3 | 85°F | 51°F | 3% | 1% | 13 h |
| September 4 | 85°F | 51°F | 3% | 1% | 13 h |
| September 5 | 85°F | 51°F | 3% | 1% | 12 h 50 min |
| September 6 | 85°F | 51°F | 4% | 1% | 12 h 50 min |
| September 7 | 85°F | 51°F | 4% | 1% | 12 h 50 min |
| September 8 | 84°F | 50°F | 4% | 1% | 12 h 50 min |
| September 9 | 84°F | 50°F | 4% | 1% | 12 h 40 min |
| September 10 | 84°F | 50°F | 4% | 2% | 12 h 40 min |
| September 11 | 84°F | 50°F | 5% | 2% | 12 h 40 min |
| September 12 | 84°F | 50°F | 5% | 2% | 12 h 40 min |
| September 13 | 84°F | 50°F | 5% | 2% | 12 h 30 min |
| September 14 | 84°F | 50°F | 5% | 2% | 12 h 30 min |
| September 15 | 84°F | 50°F | 6% | 2% | 12 h 30 min |
| September 16 | 84°F | 50°F | 6% | 2% | 12 h 30 min |
| September 17 | 83°F | 50°F | 6% | 2% | 12 h 20 min |
| September 18 | 83°F | 49°F | 6% | 2% | 12 h 20 min |
| September 19 | 83°F | 49°F | 6% | 3% | 12 h 20 min |
| September 20 | 83°F | 49°F | 7% | 3% | 12 h 20 min |
| September 21 | 83°F | 49°F | 7% | 3% | 12 h 20 min |
| September 22 | 83°F | 49°F | 7% | 3% | 12 h 10 min |
| September 23 | 83°F | 49°F | 7% | 3% | 12 h 10 min |
| September 24 | 82°F | 49°F | 8% | 3% | 12 h 10 min |
| September 25 | 82°F | 49°F | 8% | 3% | 12 h 10 min |
| September 26 | 82°F | 49°F | 8% | 3% | 12 h |
| September 27 | 82°F | 48°F | 8% | 4% | 12 h |
| September 28 | 82°F | 48°F | 9% | 4% | 12 h |
| September 29 | 81°F | 48°F | 9% | 4% | 12 h |
| September 30 | 81°F | 48°F | 9% | 4% | 11 h 50 min |
- Normal high
- 83°FSeptember average
- Normal low
- 50°FSeptember average
- Precipitation
- 0.13 inmonth total
- Days with precipitation
- 20.01 inch or more
- Days at 90°F or more
- 8
- Daylight
- 13 h to 11 h 50 minSeptember 1 to September 30
- Days at 70°F or more
- 29
- Days at 80°F or more
- 19
- Sunshine
- 93%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00023213; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in Santa Rosa in September?
On a given September day the chance of 0.01 inch or more is 6% on average, highest around September 30 (9%). In all, 0.13 in falls on 2 days of a normal September.
In a normal September in Santa Rosa, 8 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00023213.
What are the records for September in Santa Rosa?
The warmest September temperature on this station's record (since 1998) is 114°F, on September 6, 2022; the coldest is 37°F, on September 30, 2019. The wettest September brought 0.96 in (2022).
The September mean against the 1991-2020 normal of 66.5°F: 2021 66.7°F (+0.2), 2022 69.7°F (+3.2), 2023 66.0°F (−0.5), 2024 67.5°F (+1.0), 2025 68.4°F (+1.9), 2026 66.5°F (at normal). 4 of 6 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 66.7°F | +0.2°F | 0.15 in |
| 2022 | 69.7°F | +3.2°F | 0.96 in |
| 2023 | 66.0°F | −0.5°F | 0.17 in |
| 2024 | 67.5°F | +1.0°F | 0.00 in |
| 2025 | 68.4°F | +1.9°F | 0.37 in |
| 2026 | 66.5°F | at normal | 0.24 in |
Source: records: ACIS, station USW00023213; recent months: ACIS, station USW00023213. Records and recent months use complete months only.
How does September in Santa Rosa compare across California?
Across the 219 places PlainClimate covers in California, September normal highs run from 64°F in Eureka to 104°F in Brawley; Santa Rosa's is 83°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.
Other months and places
- Santa Rosa in August84°F by day, 52°F at night
- Santa Rosa in October77°F by day, 46°F at night
- Santa Rosa through the yearEvery month, frost dates, records and recent years
- California in SeptemberThe statewide normal and the warmest and coolest places
- Brawley: California's warmest Septembernormal high 104°F