September weather in Grass Valley, OR
The average temperature in Grass Valley in September is 60.6°F (45.4°F–75.8°F). Average precipitation: 0.43 inches.
September is a fall month in Grass Valley, and is warmer than the annual average of 49°F. Daily temperatures swing about 30.4°F between overnight low and afternoon high. Expect about 3 days with precipitation. Daylight averages about 12h 18m. For travel, September is a comfortable month to visit.
Avg High
75.8°F
Avg Low
45.4°F
Precipitation
0.43 in
Daylight
12h 18m
September records in Grass Valley
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 97.0°F (1998) | 36.0°F (1919) | 0.50 in (2023) |
| September 2 | 100.0°F (1998) | 37.0°F (1999) | 0.51 in (1971) |
| September 3 | 99.0°F (2017) | 28.9°F (1980) | 0.28 in (1979) |
| September 4 | 98.1°F (2017) | 36.0°F (1956) | 0.13 in (1960) |
| September 5 | 99.0°F (1988) | 34.0°F (1956) | 0.29 in (1937) |
| September 6 | 98.1°F (1955) | 34.0°F (1928) | 0.52 in (1971) |
| September 7 | 97.0°F (1944) | 35.1°F (1985) | 0.69 in (1995) |
| September 8 | 95.0°F (1944) | 34.0°F (1962) | 0.39 in (1924) |
| September 9 | 95.0°F (1944) | 33.1°F (1970) | 0.22 in (2000) |
| September 10 | 97.0°F (1944) | 34.0°F (1964) | 0.64 in (1985) |
| September 11 | 95.0°F (1944) | 34.0°F (2012) | 0.78 in (1919) |
| September 12 | 96.1°F (2011) | 28.9°F (1921) | 0.46 in (1928) |
| September 13 | 93.9°F (2013) | 30.0°F (1921) | 0.75 in (1918) |
| September 14 | 93.0°F (1938) | 32.0°F (1952) | 0.33 in (1920) |
| September 15 | 93.9°F (1938) | 30.9°F (1982) | 0.85 in (1963) |
| September 16 | 95.0°F (1938) | 32.0°F (1936) | 0.32 in (1963) |
| September 17 | 96.1°F (1938) | 26.1°F (1965) | 0.20 in (1986) |
| September 18 | 91.9°F (1981) | 28.0°F (1965) | 0.74 in (2010) |
| September 19 | 91.0°F (2012) | 32.0°F (2006) | 1.16 in (2010) |
| September 20 | 91.9°F (2012) | 28.0°F (1983) | 0.84 in (1982) |
| September 21 | 93.0°F (1939) | 23.0°F (1980) | 0.20 in (1898) |
| September 22 | 90.0°F (1938) | 30.0°F (1955) | 0.29 in (1972) |
| September 23 | 90.0°F (1952) | 24.1°F (2000) | 0.68 in (1934) |
| September 24 | 90.0°F (1952) | 21.0°F (1926) | 0.85 in (1948) |
| September 25 | 93.9°F (1952) | 26.1°F (1926) | 0.44 in (2014) |
| September 26 | 91.9°F (1994) | 23.0°F (1980) | 0.31 in (1948) |
| September 27 | 88.0°F (1994) | 27.0°F (1972) | 0.71 in (1981) |
| September 28 | 90.0°F (1967) | 28.0°F (1983) | 1.41 in (1947) |
| September 29 | 91.0°F (1967) | 26.1°F (1983) | 0.66 in (1927) |
| September 30 | 84.9°F (1970) | 24.1°F (1954) | 0.20 in (2013) |