September weather in Fairfax, IA
The average temperature in Fairfax in September is 63.3°F (51.9°F–74.7°F). Average precipitation: 3.40 inches.
September is a fall month in Fairfax, and is warmer than the annual average of 48.3°F. Daily temperatures swing about 22.8°F between overnight low and afternoon high. Expect about 9 days with precipitation. Daylight averages about 12h 16m. For travel, September is one of the best months of the year to visit.
Avg High
74.7°F
Avg Low
51.9°F
Precipitation
3.40 in
Daylight
12h 16m
September records in Fairfax
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 98.1°F (1953) | 44.1°F (1967) | 0.88 in (2018) |
| September 2 | 96.1°F (1953) | 45.0°F (1967) | 2.94 in (1973) |
| September 3 | 96.1°F (2023) | 37.0°F (1974) | 3.39 in (1958) |
| September 4 | 97.0°F (2023) | 37.9°F (1974) | 1.84 in (1980) |
| September 5 | 93.9°F (1954) | 42.1°F (1974) | 1.87 in (1975) |
| September 6 | 93.9°F (1954) | 41.0°F (2025) | 1.57 in (1982) |
| September 7 | 96.1°F (1985) | 37.9°F (1986) | 1.19 in (2016) |
| September 8 | 93.9°F (1971) | 37.9°F (1986) | 1.89 in (1989) |
| September 9 | 99.0°F (2013) | 41.0°F (1995) | 1.38 in (1986) |
| September 10 | 97.0°F (2013) | 37.0°F (1976) | 0.71 in (2022) |
| September 11 | 95.0°F (2000) | 39.9°F (1955) | 1.56 in (1963) |
| September 12 | 91.9°F (1962) | 36.0°F (1975) | 2.60 in (1961) |
| September 13 | 93.0°F (2025) | 35.1°F (1975) | 2.67 in (1961) |
| September 14 | 93.0°F (1994) | 36.0°F (1996) | 2.78 in (1967) |
| September 15 | 91.9°F (1955) | 30.9°F (2007) | 1.08 in (2016) |
| September 16 | 90.0°F (1955) | 37.0°F (1984) | 0.99 in (1987) |
| September 17 | 91.0°F (1988) | 39.0°F (1980) | 2.29 in (1977) |
| September 18 | 93.9°F (1972) | 36.0°F (2012) | 1.88 in (2015) |
| September 19 | 90.0°F (1984) | 33.1°F (1991) | 2.15 in (2002) |
| September 20 | 96.1°F (2022) | 28.9°F (1991) | 1.71 in (1965) |
| September 21 | 93.0°F (2017) | 33.1°F (1974) | 1.60 in (1973) |
| September 22 | 93.0°F (2017) | 28.9°F (1974) | 2.14 in (2000) |
| September 23 | 93.0°F (2017) | 28.9°F (2012) | 2.65 in (2016) |
| September 24 | 91.9°F (1984) | 28.0°F (2012) | 1.37 in (2005) |
| September 25 | 91.9°F (2017) | 34.0°F (2001) | 2.26 in (1993) |
| September 26 | 88.0°F (2021) | 30.0°F (1984) | 2.35 in (1959) |
| September 27 | 89.1°F (1954) | 34.0°F (1985) | 0.66 in (1999) |
| September 28 | 97.0°F (1953) | 33.1°F (1961) | 1.52 in (1972) |
| September 29 | 91.9°F (1953) | 27.0°F (1984) | 1.11 in (1995) |
| September 30 | 93.9°F (2023) | 28.0°F (2003) | 1.30 in (1961) |