September weather in Decorah, IA
The average temperature in Decorah in September is 64.4°F (52.3°F–76.4°F). Average precipitation: 3.60 inches.
September is a fall month in Decorah, and is warmer than the annual average of 48.5°F. Daily temperatures swing about 24.1°F between overnight low and afternoon high. Expect about 9 days with precipitation. Daylight averages about 12h 17m. For travel, September is one of the best months of the year to visit.
Avg High
76.4°F
Avg Low
52.3°F
Precipitation
3.60 in
Daylight
12h 17m
September records in Decorah
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 100.0°F (1913) | 33.1°F (1949) | 2.24 in (1897) |
| September 2 | 99.0°F (1913) | 37.9°F (1967) | 1.26 in (1906) |
| September 3 | 98.1°F (1939) | 36.0°F (1952) | 1.12 in (1934) |
| September 4 | 98.1°F (2023) | 35.1°F (1930) | 2.20 in (2018) |
| September 5 | 97.0°F (1913) | 37.9°F (1918) | 3.20 in (1985) |
| September 6 | 99.0°F (1922) | 37.0°F (1950) | 1.76 in (1904) |
| September 7 | 100.0°F (1939) | 33.1°F (1956) | 3.20 in (1916) |
| September 8 | 98.1°F (1933) | 36.0°F (1949) | 2.78 in (2001) |
| September 9 | 100.0°F (1955) | 35.1°F (1924) | 2.38 in (2016) |
| September 10 | 96.1°F (1895) | 34.0°F (1967) | 3.71 in (1919) |
| September 11 | 97.0°F (1895) | 28.0°F (1955) | 2.21 in (2006) |
| September 12 | 96.1°F (1931) | 28.0°F (1955) | 1.61 in (1991) |
| September 13 | 96.1°F (1927) | 30.9°F (1902) | 2.63 in (2019) |
| September 14 | 97.0°F (1939) | 28.0°F (1923) | 2.15 in (1928) |
| September 15 | 96.1°F (1939) | 30.0°F (2007) | 1.56 in (1921) |
| September 16 | 98.1°F (1931) | 32.0°F (1916) | 2.41 in (2016) |
| September 17 | 93.9°F (1955) | 32.0°F (1916) | 1.26 in (1997) |
| September 18 | 93.9°F (1955) | 27.0°F (1929) | 2.51 in (1907) |
| September 19 | 96.1°F (1948) | 28.0°F (1929) | 1.54 in (1923) |
| September 20 | 93.0°F (1931) | 28.0°F (1897) | 2.40 in (1931) |
| September 21 | 96.1°F (1937) | 30.0°F (1999) | 4.79 in (1986) |
| September 22 | 96.1°F (1937) | 25.0°F (1974) | 3.22 in (2016) |
| September 23 | 93.9°F (2017) | 28.0°F (1995) | 3.44 in (2023) |
| September 24 | 93.0°F (2017) | 28.0°F (2012) | 1.90 in (1910) |
| September 25 | 91.0°F (2017) | 25.0°F (1926) | 4.56 in (1972) |
| September 26 | 88.0°F (1986) | 18.0°F (1926) | 2.14 in (1972) |
| September 27 | 86.0°F (1929) | 28.0°F (1957) | 1.95 in (1916) |
| September 28 | 89.1°F (1939) | 25.0°F (1930) | 1.38 in (1901) |
| September 29 | 88.0°F (1953) | 21.0°F (1949) | 1.41 in (1923) |
| September 30 | 91.0°F (2023) | 18.0°F (1899) | 1.45 in (1961) |