September weather in Napa, CA
The average temperature in Napa in September is 68.9°F (53.4°F–84.4°F). Average precipitation: 0.09 inches.
September is a fall month in Napa, and is warmer than the annual average of 60.3°F. Daily temperatures swing about 31°F between overnight low and afternoon high. Expect about 1 days with precipitation. Daylight averages about 12h 14m. For travel, September is a comfortable month to visit.
Avg High
84.4°F
Avg Low
53.4°F
Precipitation
0.09 in
Daylight
12h 14m
September records in Napa
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 107.1°F (1955) | 44.1°F (1901) | 0.04 in (2000) |
| September 2 | 109.0°F (1955) | 41.0°F (1928) | 0.00 in (1893) |
| September 3 | 108.0°F (2017) | 39.9°F (1917) | 0.20 in (1940) |
| September 4 | 105.1°F (1950) | 42.1°F (1932) | 0.08 in (1900) |
| September 5 | 109.0°F (2022) | 42.1°F (1932) | 0.03 in (1893) |
| September 6 | 114.1°F (2022) | 42.1°F (1898) | 1.50 in (1912) |
| September 7 | 111.0°F (2020) | 43.0°F (1932) | 1.02 in (1912) |
| September 8 | 108.0°F (1904) | 42.1°F (1928) | 0.16 in (1930) |
| September 9 | 109.0°F (1944) | 39.9°F (1931) | 0.33 in (1978) |
| September 10 | 105.1°F (1944) | 37.9°F (1993) | 0.50 in (1978) |
| September 11 | 107.1°F (1979) | 43.0°F (1931) | 0.24 in (1985) |
| September 12 | 107.1°F (1979) | 42.1°F (1946) | 1.44 in (1918) |
| September 13 | 107.1°F (1971) | 39.0°F (1921) | 1.21 in (1918) |
| September 14 | 108.0°F (1971) | 39.9°F (1921) | 0.14 in (2009) |
| September 15 | 106.0°F (1971) | 41.0°F (1936) | 0.42 in (1955) |
| September 16 | 104.0°F (1913) | 43.0°F (1936) | 1.00 in (1982) |
| September 17 | 102.0°F (1913) | 42.1°F (1952) | 0.84 in (1989) |
| September 18 | 102.9°F (1912) | 42.1°F (1926) | 1.87 in (1959) |
| September 19 | 104.0°F (1919) | 37.0°F (1926) | 0.51 in (1977) |
| September 20 | 105.1°F (1939) | 39.9°F (1917) | 0.15 in (2022) |
| September 21 | 105.1°F (1939) | 42.1°F (1924) | 0.67 in (2013) |
| September 22 | 105.1°F (1939) | 36.0°F (1932) | 0.40 in (1923) |
| September 23 | 106.0°F (1939) | 39.0°F (1932) | 1.98 in (1904) |
| September 24 | 104.0°F (1964) | 39.0°F (1932) | 1.35 in (1904) |
| September 25 | 100.9°F (1960) | 39.0°F (1934) | 0.64 in (1904) |
| September 26 | 105.1°F (1963) | 37.9°F (1929) | 1.01 in (1972) |
| September 27 | 100.9°F (1921) | 39.9°F (1900) | 0.52 in (1957) |
| September 28 | 102.0°F (1921) | 39.9°F (1929) | 0.70 in (1957) |
| September 29 | 100.9°F (1966) | 37.9°F (1929) | 0.48 in (1930) |
| September 30 | 100.0°F (1980) | 39.9°F (1925) | 1.23 in (1894) |