September weather in Union, IA
The average temperature in Union in September is 63.0°F (50.5°F–75.5°F). Average precipitation: 3.56 inches.
September is a fall month in Union, and is warmer than the annual average of 46.9°F. Daily temperatures swing about 25°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
75.5°F
Avg Low
50.5°F
Precipitation
3.56 in
Daylight
12h 16m
September records in Union
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 96.1°F (2000) | 42.1°F (1967) | 1.50 in (2010) |
| September 2 | 98.1°F (1984) | 43.0°F (1967) | 0.80 in (1949) |
| September 3 | 95.0°F (2000) | 37.0°F (1974) | 1.26 in (1961) |
| September 4 | 95.0°F (2000) | 37.0°F (1974) | 1.13 in (1968) |
| September 5 | 95.0°F (2012) | 35.1°F (1962) | 3.20 in (1956) |
| September 6 | 93.9°F (1998) | 36.0°F (1962) | 2.07 in (2004) |
| September 7 | 95.0°F (1985) | 39.0°F (1986) | 2.55 in (2001) |
| September 8 | 97.0°F (1978) | 39.0°F (1986) | 3.72 in (2001) |
| September 9 | 93.0°F (1978) | 41.0°F (1986) | 1.25 in (2020) |
| September 10 | 98.1°F (2013) | 37.9°F (1959) | 1.18 in (2019) |
| September 11 | 95.0°F (2013) | 34.0°F (1959) | 4.15 in (2006) |
| September 12 | 98.1°F (2000) | 36.0°F (1959) | 2.56 in (2003) |
| September 13 | 96.1°F (1998) | 34.0°F (2014) | 4.64 in (1991) |
| September 14 | 91.9°F (2000) | 34.0°F (2014) | 1.08 in (1978) |
| September 15 | 90.0°F (1994) | 33.1°F (2007) | 1.84 in (1970) |
| September 16 | 91.0°F (2017) | 34.0°F (2007) | 1.66 in (2016) |
| September 17 | 88.0°F (1972) | 37.0°F (2014) | 0.97 in (2001) |
| September 18 | 95.0°F (1988) | 34.0°F (1959) | 1.05 in (2015) |
| September 19 | 89.1°F (1985) | 33.1°F (1991) | 1.23 in (2010) |
| September 20 | 93.0°F (1984) | 32.0°F (1962) | 7.45 in (1950) |
| September 21 | 96.1°F (2022) | 30.9°F (1991) | 1.03 in (1965) |
| September 22 | 93.0°F (2005) | 28.0°F (1974) | 1.30 in (2009) |
| September 23 | 91.9°F (2017) | 28.9°F (1983) | 1.62 in (2016) |
| September 24 | 91.9°F (2017) | 28.9°F (1989) | 1.09 in (1960) |
| September 25 | 91.0°F (2017) | 30.9°F (1989) | 3.10 in (2009) |
| September 26 | 86.0°F (1990) | 30.0°F (1984) | 1.80 in (1996) |
| September 27 | 88.0°F (1998) | 28.9°F (1984) | 1.27 in (1965) |
| September 28 | 84.9°F (1983) | 28.9°F (1961) | 0.47 in (1973) |
| September 29 | 86.0°F (1971) | 28.0°F (1984) | 0.93 in (1954) |
| September 30 | 89.1°F (2021) | 30.0°F (1967) | 2.38 in (1961) |