Santa Rosa Weather in September
Average highs run from 89°F on September 1 to 81°F on September 30, and lows from 57°F to 48°F. Normal precipitation for the month is 1.99 in over about 6 wet days.
September day by day
The normal high and low for each date, and the record, in °F.
- Normal low
- Normal high
- Record high
- Record low
September at a glance
- Average high
- 85°F
- Average low
- 53°F
- Precipitation
- 1.99 in
- Record high
- 100°FSep 1, 1936
- Record low
- 29°FSep 29, 1999
- Chance of a freeze
- 2%
- Days of 90°F or more
- 7.5
- Daylight
- 12 h 53 min to 11 h 51 min
- Cloud cover
- 39%
- Humidity
- 49%
- Dew point
- 46°F
- Wind
- 9.6 mph
Every day of the month
A wet day has at least 0.01 inch of precipitation; snow means at least 0.1 inch of snowfall.
| Date | Normal high | Normal low | Record high | Record low | Chance wet | Chance of snow |
|---|---|---|---|---|---|---|
| Sep 1 | 89°F | 57°F | 100°F 1936 | 46°F 2000 | 22% | 0% |
| Sep 2 | 89°F | 57°F | 99°F 1983 | 49°F 1955 | 21% | 0% |
| Sep 3 | 89°F | 57°F | 100°F 1931 | 46°F 1974 | 21% | 0% |
| Sep 4 | 89°F | 57°F | 100°F 1931 | 34°F 1961 | 21% | 0% |
| Sep 5 | 89°F | 56°F | 100°F 1995 | 39°F 1961 | 21% | 0% |
| Sep 6 | 88°F | 56°F | 100°F 1995 | 46°F 2004 | 21% | 0% |
| Sep 7 | 88°F | 56°F | 98°F 1995 | 46°F 1920 | 21% | 0% |
| Sep 8 | 88°F | 56°F | 96°F 1977 | 40°F 2001 | 21% | 0% |
| Sep 9 | 88°F | 55°F | 97°F 1955 | 42°F 2001 | 20% | 0% |
| Sep 10 | 87°F | 55°F | 98°F 1984 | 40°F 2001 | 20% | 0% |
| Sep 11 | 87°F | 55°F | 97°F 1974 | 43°F 1920 | 20% | 0% |
| Sep 12 | 87°F | 54°F | 96°F 1924 | 42°F 2003 | 20% | 0% |
| Sep 13 | 86°F | 54°F | 98°F 1955 | 40°F 1959 | 20% | 0% |
| Sep 14 | 86°F | 54°F | 100°F 1956 | 38°F 1959 | 19% | 0% |
| Sep 15 | 86°F | 53°F | 100°F 1956 | 40°F 1947 | 19% | 0% |
| Sep 16 | 85°F | 53°F | 100°F 1956 | 40°F 1951 | 19% | 0% |
| Sep 17 | 85°F | 53°F | 97°F 1954 | 40°F 1968 | 19% | 0% |
| Sep 18 | 85°F | 52°F | 97°F 1954 | 35°F 1971 | 18% | 0% |
| Sep 19 | 84°F | 52°F | 97°F 1954 | 36°F 2003 | 18% | 0% |
| Sep 20 | 84°F | 52°F | 96°F 1956 | 35°F 1971 | 18% | 0% |
| Sep 21 | 84°F | 51°F | 93°F 1981 | 33°F 1983 | 17% | 0% |
| Sep 22 | 84°F | 51°F | 93°F 1930 | 36°F 1924 | 17% | 0% |
| Sep 23 | 83°F | 50°F | 93°F 2012 | 34°F 1924 | 17% | 0% |
| Sep 24 | 83°F | 50°F | 94°F 1966 | 37°F 1957 | 16% | 0% |
| Sep 25 | 83°F | 50°F | 94°F 1924 | 30°F 2000 | 16% | 0% |
| Sep 26 | 82°F | 49°F | 94°F 2003 | 32°F 2000 | 16% | 0% |
| Sep 27 | 82°F | 49°F | 98°F 2005 | 34°F 1936 | 15% | 0% |
| Sep 28 | 82°F | 49°F | 95°F 1994 | 33°F 1924 | 15% | 0% |
| Sep 29 | 81°F | 48°F | 94°F 1994 | 29°F 1999 | 15% | 0% |
| Sep 30 | 81°F | 48°F | 92°F 2003 | 33°F 1999 | 14% | 0% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (MDT).
- September 1
- sunrise 6:32 AM, sunset 7:25 PM
- September 30
- sunrise 6:53 AM, sunset 6:44 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00298107 (Santa Rosa), public domain. Records: NOAA GHCN-Daily, station USC00298107, every year on file, quality-flagged values removed. Cloud, humidity, wind and sunshine: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-25. Sun and moon: computed with the NOAA solar equations and Meeus.