Cotati Weather in September
Average highs run from 82°F on September 1 to 80°F on September 30, and lows from 52°F to 50°F. Normal precipitation for the month is 0.09 in over about 1 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
- 82°F
- Average low
- 51°F
- Precipitation
- 0.09 in
- Record high
- 109°FSep 6, 2022
- Record low
- 31°FSep 19, 1929
- Chance of a freeze
- 0%
- Days of 90°F or more
- 6.4
- Daylight
- 12 h 59 min to 11 h 49 min
- Cloud cover
- 26%
- Humidity
- 47%
- Dew point
- 43°F
- Wind
- 6.5 mph
Every day of the month
A wet day has at least 0.01 inch of precipitation.
| Date | Normal high | Normal low | Record high | Record low | Chance wet |
|---|---|---|---|---|---|
| Sep 1 | 82°F | 52°F | 107°F 2017 | 40°F 2011 | 2% |
| Sep 2 | 82°F | 52°F | 107°F 1955 | 39°F 1965 | 2% |
| Sep 3 | 82°F | 52°F | 108°F 1955 | 39°F 1919 | 2% |
| Sep 4 | 82°F | 52°F | 100°F 1975 | 39°F 1948 | 2% |
| Sep 5 | 82°F | 52°F | 108°F 2022 | 37°F 1948 | 2% |
| Sep 6 | 82°F | 52°F | 109°F 2022 | 44°F 1914 | 3% |
| Sep 7 | 82°F | 52°F | 105°F 1957 | 43°F 1960 | 3% |
| Sep 8 | 82°F | 52°F | 103°F 1984 | 44°F 1915 | 3% |
| Sep 9 | 82°F | 52°F | 108°F 1944 | 42°F 1914 | 3% |
| Sep 10 | 82°F | 52°F | 103°F 2022 | 42°F 1937 | 3% |
| Sep 11 | 82°F | 52°F | 104°F 1979 | 41°F 1928 | 3% |
| Sep 12 | 82°F | 52°F | 108°F 1979 | 37°F 1985 | 3% |
| Sep 13 | 82°F | 52°F | 109°F 1971 | 39°F 1970 | 3% |
| Sep 14 | 82°F | 52°F | 109°F 1971 | 39°F 1970 | 4% |
| Sep 15 | 82°F | 52°F | 109°F 1971 | 41°F 1970 | 4% |
| Sep 16 | 82°F | 52°F | 109°F 1913 | 40°F 1936 | 4% |
| Sep 17 | 82°F | 51°F | 105°F 1913 | 40°F 1926 | 4% |
| Sep 18 | 82°F | 51°F | 106°F 1913 | 36°F 1929 | 4% |
| Sep 19 | 82°F | 51°F | 107°F 1919 | 31°F 1929 | 4% |
| Sep 20 | 82°F | 51°F | 103°F 1943 | 33°F 1929 | 4% |
| Sep 21 | 81°F | 51°F | 104°F 1939 | 39°F 1929 | 5% |
| Sep 22 | 81°F | 51°F | 103°F 1939 | 38°F 1924 | 5% |
| Sep 23 | 81°F | 51°F | 103°F 1936 | 37°F 1929 | 5% |
| Sep 24 | 81°F | 51°F | 104°F 1964 | 38°F 1929 | 5% |
| Sep 25 | 81°F | 51°F | 101°F 1960 | 38°F 1926 | 5% |
| Sep 26 | 81°F | 51°F | 102°F 1963 | 37°F 1934 | 6% |
| Sep 27 | 81°F | 50°F | 103°F 1921 | 37°F 1924 | 6% |
| Sep 28 | 81°F | 50°F | 102°F 1921 | 38°F 1924 | 6% |
| Sep 29 | 80°F | 50°F | 100°F 1966 | 38°F 1924 | 6% |
| Sep 30 | 80°F | 50°F | 103°F 1980 | 38°F 1924 | 6% |
Chance of rain
- Chance of a wet day
Sunrise and sunset
Times for 2026, local time (PDT).
- September 1
- sunrise 6:41 AM, sunset 7:40 PM
- September 30
- sunrise 7:06 AM, sunset 6:55 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00046826 (Petaluma AP), public domain. Records: NOAA GHCN-Daily, station USC00046826, 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 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.