September weather in San Mateo, CA
The average temperature in San Mateo in September is 65.3°F (55.9°F–74.8°F). Average precipitation: 0.07 inches.
September is a fall month in San Mateo, and is warmer than the annual average of 58.7°F. Daily temperatures swing about 18.9°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
74.8°F
Avg Low
55.9°F
Precipitation
0.07 in
Daylight
12h 14m
September records in San Mateo
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 104.0°F (2017) | 48.9°F (1957) | 0.07 in (2000) |
| September 2 | 104.0°F (2017) | 48.9°F (1946) | 0.00 in (1945) |
| September 3 | 93.0°F (1961) | 50.0°F (1945) | 0.00 in (1945) |
| September 4 | 91.9°F (1961) | 50.0°F (1947) | 0.00 in (1945) |
| September 5 | 97.0°F (2022) | 45.0°F (1954) | 0.03 in (1945) |
| September 6 | 102.0°F (2020) | 46.9°F (1950) | 0.02 in (1969) |
| September 7 | 97.0°F (2020) | 50.0°F (1960) | 0.00 in (1945) |
| September 8 | 100.0°F (1984) | 48.0°F (1946) | 0.17 in (1985) |
| September 9 | 91.9°F (1951) | 46.0°F (1946) | 0.26 in (1978) |
| September 10 | 93.9°F (1979) | 48.9°F (1947) | 0.00 in (1945) |
| September 11 | 98.1°F (1979) | 48.9°F (1951) | 0.22 in (2017) |
| September 12 | 100.0°F (1979) | 46.9°F (1946) | 0.07 in (1963) |
| September 13 | 100.9°F (1971) | 46.9°F (1947) | 0.27 in (2009) |
| September 14 | 102.9°F (1971) | 46.0°F (1947) | 0.00 in (1945) |
| September 15 | 98.1°F (1971) | 48.0°F (1970) | 0.00 in (1945) |
| September 16 | 90.0°F (1968) | 48.9°F (2006) | 0.88 in (1989) |
| September 17 | 93.9°F (1984) | 50.0°F (1945) | 0.28 in (1982) |
| September 18 | 93.0°F (2009) | 46.0°F (1955) | 2.29 in (1959) |
| September 19 | 93.0°F (2000) | 46.0°F (1947) | 0.46 in (1977) |
| September 20 | 93.0°F (1983) | 48.0°F (1947) | 0.08 in (2005) |
| September 21 | 95.0°F (2003) | 45.0°F (1955) | 0.23 in (2013) |
| September 22 | 91.0°F (1946) | 48.0°F (1981) | 0.20 in (1990) |
| September 23 | 91.9°F (1978) | 45.0°F (1972) | 0.31 in (1982) |
| September 24 | 93.9°F (2019) | 48.0°F (1945) | 0.18 in (1986) |
| September 25 | 96.1°F (2019) | 46.9°F (1948) | 0.41 in (2014) |
| September 26 | 95.0°F (1958) | 46.0°F (1948) | 0.27 in (1972) |
| September 27 | 96.1°F (1958) | 46.9°F (1948) | 0.81 in (1957) |
| September 28 | 96.1°F (2020) | 46.9°F (1947) | 0.17 in (1976) |
| September 29 | 95.0°F (2020) | 45.0°F (1950) | 0.11 in (1971) |
| September 30 | 93.9°F (1980) | 41.0°F (1950) | 0.56 in (1983) |