September weather in Herndon, VA
The average temperature in Herndon in September is 68.6°F (57.9°F–79.3°F). Average precipitation: 3.94 inches.
September is a fall month in Herndon, and is warmer than the annual average of 55.7°F. Daily temperatures swing about 21.4°F between overnight low and afternoon high. Expect about 9 days with precipitation. Daylight averages about 12h 14m. For travel, September is one of the best months of the year to visit.
Avg High
79.3°F
Avg Low
57.9°F
Precipitation
3.94 in
Daylight
12h 14m
September records in Herndon
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 98.1°F (1962) | 48.9°F (1970) | 2.76 in (2006) |
| September 2 | 99.0°F (1980) | 44.1°F (1970) | 0.97 in (1969) |
| September 3 | 99.0°F (2023) | 45.0°F (1967) | 1.47 in (1969) |
| September 4 | 99.0°F (2023) | 48.0°F (1997) | 1.29 in (1996) |
| September 5 | 99.0°F (2023) | 42.1°F (1997) | 3.78 in (1979) |
| September 6 | 100.0°F (2023) | 45.0°F (1972) | 5.11 in (2008) |
| September 7 | 97.0°F (2023) | 41.0°F (1976) | 1.11 in (2011) |
| September 8 | 96.1°F (2016) | 43.0°F (1984) | 3.56 in (1987) |
| September 9 | 98.1°F (2016) | 39.9°F (1986) | 1.40 in (2018) |
| September 10 | 99.0°F (1983) | 43.0°F (1981) | 1.50 in (1968) |
| September 11 | 99.0°F (1983) | 39.9°F (1976) | 1.45 in (2023) |
| September 12 | 95.0°F (1998) | 39.9°F (1967) | 1.18 in (1965) |
| September 13 | 93.9°F (1974) | 43.0°F (1985) | 0.68 in (1983) |
| September 14 | 95.0°F (1998) | 37.0°F (1985) | 5.52 in (1966) |
| September 15 | 95.0°F (1993) | 37.9°F (1985) | 1.06 in (1981) |
| September 16 | 97.0°F (1991) | 37.0°F (1984) | 2.05 in (1999) |
| September 17 | 97.0°F (1991) | 35.1°F (1986) | 1.71 in (2004) |
| September 18 | 91.0°F (1978) | 37.0°F (1990) | 1.76 in (2003) |
| September 19 | 93.0°F (1977) | 36.0°F (1984) | 1.26 in (2000) |
| September 20 | 91.0°F (1965) | 39.9°F (1979) | 0.87 in (1966) |
| September 21 | 91.9°F (1965) | 33.1°F (1962) | 2.59 in (1979) |
| September 22 | 93.9°F (1970) | 35.1°F (1962) | 1.57 in (1982) |
| September 23 | 93.9°F (2019) | 33.1°F (1983) | 1.74 in (2003) |
| September 24 | 97.0°F (2010) | 30.0°F (1974) | 2.17 in (2001) |
| September 25 | 93.0°F (2010) | 33.1°F (1983) | 2.67 in (1975) |
| September 26 | 93.0°F (2007) | 37.9°F (1964) | 2.15 in (1975) |
| September 27 | 96.1°F (1998) | 35.1°F (1984) | 1.55 in (1985) |
| September 28 | 86.0°F (1998) | 34.0°F (1989) | 1.61 in (2004) |
| September 29 | 89.1°F (2019) | 34.0°F (1978) | 2.23 in (1963) |
| September 30 | 91.9°F (1986) | 35.1°F (1993) | 4.74 in (2010) |