September weather in Sunnyvale, CA
The average temperature in Sunnyvale in September is 67.5°F (57.3°F–77.7°F). Average precipitation: 0.07 inches.
September is a fall month in Sunnyvale, and is warmer than the annual average of 59.9°F. Daily temperatures swing about 20.4°F between overnight low and afternoon high. Expect about 1 days with precipitation. Daylight averages about 12h 14m. For travel, September is one of the best months of the year to visit.
Avg High
77.7°F
Avg Low
57.3°F
Precipitation
0.07 in
Daylight
12h 14m
September records in Sunnyvale
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 106.0°F (2017) | 48.9°F (1975) | 0.05 in (2000) |
| September 2 | 106.0°F (2017) | 48.9°F (1970) | 0.00 in (1945) |
| September 3 | 93.0°F (1961) | 48.9°F (1970) | 0.00 in (1945) |
| September 4 | 96.1°F (2008) | 46.9°F (1954) | 0.00 in (1945) |
| September 5 | 97.0°F (2008) | 48.0°F (1954) | 0.06 in (2000) |
| September 6 | 95.0°F (2004) | 50.0°F (1946) | 0.10 in (1969) |
| September 7 | 95.0°F (1976) | 46.9°F (1946) | 0.08 in (1969) |
| September 8 | 100.0°F (1984) | 48.9°F (1946) | 0.20 in (1985) |
| September 9 | 97.0°F (1984) | 48.0°F (1964) | 0.07 in (1985) |
| September 10 | 96.1°F (1979) | 48.9°F (1954) | 0.00 in (1945) |
| September 11 | 102.9°F (1979) | 48.0°F (1946) | 0.06 in (2017) |
| September 12 | 100.0°F (1979) | 41.0°F (1946) | 0.14 in (1963) |
| September 13 | 98.1°F (1971) | 50.0°F (1946) | 0.22 in (2009) |
| September 14 | 105.1°F (1971) | 46.9°F (1970) | 0.00 in (1945) |
| September 15 | 99.0°F (1971) | 46.0°F (1955) | 0.00 in (1945) |
| September 16 | 93.0°F (1968) | 46.9°F (1948) | 0.40 in (1989) |
| September 17 | 93.9°F (2000) | 48.9°F (1949) | 0.12 in (1986) |
| September 18 | 93.9°F (2000) | 46.0°F (1954) | 1.96 in (1959) |
| September 19 | 96.1°F (2000) | 46.0°F (1947) | 0.47 in (1977) |
| September 20 | 96.1°F (1990) | 45.0°F (1947) | 0.02 in (1973) |
| September 21 | 97.0°F (2003) | 48.0°F (1960) | 0.49 in (2013) |
| September 22 | 93.9°F (2003) | 46.9°F (1948) | 0.29 in (2007) |
| September 23 | 95.0°F (1978) | 44.1°F (1945) | 0.42 in (1982) |
| September 24 | 95.0°F (1978) | 43.0°F (1945) | 0.21 in (1986) |
| September 25 | 96.1°F (2016) | 43.0°F (1948) | 0.41 in (2014) |
| September 26 | 95.0°F (1958) | 42.1°F (1948) | 0.36 in (1986) |
| September 27 | 93.9°F (2010) | 43.0°F (1948) | 0.39 in (1972) |
| September 28 | 96.1°F (2010) | 46.9°F (1971) | 0.26 in (1976) |
| September 29 | 93.9°F (1966) | 43.0°F (1955) | 0.12 in (1976) |
| September 30 | 95.0°F (2001) | 42.1°F (1950) | 1.14 in (1983) |