Grass Valley Weather in September
Average highs run from 86°F on September 1 to 78°F on September 30, and lows from 55°F to 49°F. Normal precipitation for the month is 0.44 in over about 2 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
- 52°F
- Precipitation
- 0.44 in
- Record high
- 107°FSep 7, 2022
- Record low
- 27°FSep 30, 1925
- Chance of a freeze
- 0%
- Days of 90°F or more
- 5.3
- Daylight
- 13 h 02 min to 11 h 48 min
- Cloud cover
- 25%
- Humidity
- 35%
- Dew point
- 40°F
- Wind
- 6.0 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 | 86°F | 55°F | 101°F 1955 | 37°F 2016 | 3% | 0% |
| Sep 2 | 85°F | 55°F | 102°F 1955 | 33°F 1939 | 3% | 0% |
| Sep 3 | 85°F | 54°F | 102°F 1950 | 32°F 1937 | 3% | 0% |
| Sep 4 | 85°F | 54°F | 102°F 1950 | 36°F 1938 | 3% | 0% |
| Sep 5 | 85°F | 54°F | 103°F 1955 | 32°F 1919 | 4% | 0% |
| Sep 6 | 85°F | 54°F | 106°F 2022 | 34°F 1937 | 4% | 0% |
| Sep 7 | 85°F | 54°F | 107°F 2022 | 32°F 1927 | 4% | 0% |
| Sep 8 | 84°F | 54°F | 100°F 1944 | 32°F 1927 | 4% | 0% |
| Sep 9 | 84°F | 54°F | 102°F 1944 | 29°F 1931 | 4% | 0% |
| Sep 10 | 84°F | 53°F | 102°F 1944 | 31°F 1931 | 4% | 0% |
| Sep 11 | 84°F | 53°F | 101°F 1945 | 31°F 1928 | 4% | 0% |
| Sep 12 | 83°F | 53°F | 101°F 1945 | 31°F 1919 | 5% | 0% |
| Sep 13 | 83°F | 53°F | 105°F 1945 | 31°F 1939 | 5% | 0% |
| Sep 14 | 83°F | 53°F | 100°F 1932 | 29°F 1927 | 5% | 0% |
| Sep 15 | 83°F | 52°F | 99°F 1929 | 32°F 1921 | 5% | 0% |
| Sep 16 | 82°F | 52°F | 101°F 1929 | 33°F 1970 | 5% | 0% |
| Sep 17 | 82°F | 52°F | 101°F 1913 | 29°F 1965 | 6% | 0% |
| Sep 18 | 82°F | 52°F | 98°F 1913 | 29°F 1947 | 6% | 0% |
| Sep 19 | 82°F | 52°F | 99°F 1939 | 31°F 1926 | 6% | 0% |
| Sep 20 | 81°F | 51°F | 98°F 1919 | 30°F 1941 | 6% | 0% |
| Sep 21 | 81°F | 51°F | 98°F 1939 | 29°F 1934 | 7% | 0% |
| Sep 22 | 81°F | 51°F | 98°F 1939 | 30°F 1934 | 7% | 0% |
| Sep 23 | 81°F | 51°F | 99°F 1943 | 28°F 1931 | 7% | 0% |
| Sep 24 | 80°F | 50°F | 97°F 1943 | 30°F 1929 | 8% | 0% |
| Sep 25 | 80°F | 50°F | 99°F 1936 | 29°F 1948 | 8% | 0% |
| Sep 26 | 80°F | 50°F | 95°F 1944 | 29°F 1948 | 8% | 0% |
| Sep 27 | 79°F | 50°F | 98°F 1944 | 29°F 1948 | 8% | 0% |
| Sep 28 | 79°F | 49°F | 95°F 1921 | 30°F 1945 | 9% | 0% |
| Sep 29 | 79°F | 49°F | 94°F 2010 | 30°F 1905 | 9% | 0% |
| Sep 30 | 78°F | 49°F | 96°F 2010 | 27°F 1925 | 9% | 0% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (PDT).
- September 1
- sunrise 6:33 AM, sunset 7:35 PM
- September 30
- sunrise 7:00 AM, sunset 6:48 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00043573 (Grass Valley #2), public domain. Records: NOAA GHCN-Daily, station USC00046136, 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.