Santa Rosa Weather in September
Average highs run from 31°C on September 1 to 33°C on September 30, and lows from 15°C to 18°C. Normal precipitation for the month is 12 mm over about 3 wet days.
September day by day
The normal high and low for each date, in °C.
- Normal low
- Normal high
- Reanalysis extreme high
- Reanalysis extreme low
September at a glance
- Average high
- 32°C
- Average low
- 16°C
- Precipitation
- 12 mm
- Reanalysis high
- 44°CSep 26, 2020
- Reanalysis low
- 5°CSep 3, 2005
- Daylight
- 11 h 39 min to 12 h 18 min
- Cloud cover
- 50%
- Humidity
- 38%
- Dew point
- 7°C
- Wind
- 12.6 km/h
Every day of the month
A wet day has at least 1 mm of precipitation in the reanalysis.
| Date | Normal high | Normal low | Reanalysis high | Reanalysis low | Chance wet |
|---|---|---|---|---|---|
| Sep 1 | 31°C | 15°C | 40°C 2004 | 5°C 1993 | 5% |
| Sep 2 | 31°C | 15°C | 42°C 2008 | 5°C 2005 | 5% |
| Sep 3 | 32°C | 15°C | 40°C 2011 | 5°C 2005 | 5% |
| Sep 4 | 32°C | 15°C | 42°C 2004 | 5°C 2016 | 5% |
| Sep 5 | 32°C | 15°C | 40°C 2004 | 5°C 2006 | 6% |
| Sep 6 | 32°C | 15°C | 43°C 2004 | 5°C 2016 | 6% |
| Sep 7 | 31°C | 15°C | 43°C 1997 | 6°C 2008 | 6% |
| Sep 8 | 31°C | 15°C | 42°C 1997 | 8°C 2002 | 4% |
| Sep 9 | 32°C | 15°C | 41°C 2014 | 8°C 2003 | 4% |
| Sep 10 | 32°C | 15°C | 40°C 2000 | 7°C 2003 | 4% |
| Sep 11 | 32°C | 15°C | 41°C 2006 | 6°C 2003 | 4% |
| Sep 12 | 32°C | 15°C | 42°C 2016 | 6°C 2005 | 4% |
| Sep 13 | 32°C | 16°C | 39°C 1994 | 8°C 2005 | 4% |
| Sep 14 | 32°C | 16°C | 39°C 2012 | 7°C 2005 | 4% |
| Sep 15 | 32°C | 16°C | 43°C 2019 | 8°C 2005 | 5% |
| Sep 16 | 32°C | 16°C | 40°C 2012 | 9°C 2005 | 6% |
| Sep 17 | 32°C | 16°C | 41°C 2002 | 7°C 2001 | 7% |
| Sep 18 | 32°C | 16°C | 40°C 2004 | 6°C 2013 | 8% |
| Sep 19 | 32°C | 16°C | 42°C 2003 | 8°C 1998 | 9% |
| Sep 20 | 33°C | 16°C | 44°C 2000 | 7°C 1998 | 9% |
| Sep 21 | 33°C | 16°C | 42°C 2010 | 6°C 1995 | 10% |
| Sep 22 | 33°C | 16°C | 42°C 2018 | 8°C 1998 | 11% |
| Sep 23 | 33°C | 17°C | 44°C 2018 | 8°C 2013 | 12% |
| Sep 24 | 33°C | 17°C | 42°C 1994 | 8°C 2013 | 12% |
| Sep 25 | 33°C | 17°C | 44°C 2020 | 7°C 2013 | 13% |
| Sep 26 | 33°C | 17°C | 44°C 2020 | 8°C 1996 | 14% |
| Sep 27 | 33°C | 17°C | 40°C 2004 | 11°C 1996 | 14% |
| Sep 28 | 33°C | 17°C | 41°C 2008 | 10°C 2009 | 15% |
| Sep 29 | 33°C | 17°C | 43°C 2018 | 9°C 2009 | 16% |
| Sep 30 | 33°C | 18°C | 43°C 2020 | 8°C 2009 | 15% |
Chance of rain
- Chance of a wet day
Sunrise and sunset
Times for 2026, local time (GMT-3).
- September 1
- sunrise 7:28 AM, sunset 7:07 PM
- September 30
- sunrise 6:59 AM, sunset 7:17 PM
Other months
Sources
Cloud, humidity, wind and sunshine, and temperature and precipitation: 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.