September weather in Diagonal, IA
The average temperature in Diagonal in September is 64.5°F (52.7°F–76.4°F). Average precipitation: 3.71 inches.
September is a fall month in Diagonal, and is warmer than the annual average of 49.6°F. Daily temperatures swing about 23.7°F between overnight low and afternoon high. Expect about 7 days with precipitation. Daylight averages about 12h 15m. For travel, September is one of the best months of the year to visit.
Avg High
76.4°F
Avg Low
52.7°F
Precipitation
3.71 in
Daylight
12h 15m
September records in Diagonal
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 100.9°F (1913) | 37.0°F (1949) | 4.00 in (2018) |
| September 2 | 100.9°F (1913) | 45.0°F (1952) | 3.15 in (1992) |
| September 3 | 100.9°F (1913) | 37.9°F (1952) | 2.86 in (1926) |
| September 4 | 104.0°F (1913) | 39.9°F (1974) | 1.23 in (1975) |
| September 5 | 105.1°F (1913) | 37.9°F (1962) | 3.75 in (1936) |
| September 6 | 100.0°F (1939) | 37.0°F (1988) | 3.18 in (1964) |
| September 7 | 100.9°F (1939) | 36.0°F (1956) | 1.75 in (2015) |
| September 8 | 99.0°F (1947) | 37.0°F (1986) | 2.79 in (1926) |
| September 9 | 97.0°F (1897) | 37.0°F (2008) | 3.64 in (1989) |
| September 10 | 96.1°F (1906) | 39.0°F (1940) | 4.00 in (2014) |
| September 11 | 96.1°F (2013) | 37.0°F (1940) | 1.91 in (1925) |
| September 12 | 99.0°F (1897) | 34.0°F (1902) | 4.68 in (1949) |
| September 13 | 98.1°F (1897) | 32.0°F (1902) | 3.72 in (2008) |
| September 14 | 96.1°F (1939) | 33.1°F (2014) | 5.00 in (1914) |
| September 15 | 97.0°F (1939) | 35.1°F (1961) | 2.88 in (1941) |
| September 16 | 93.9°F (1906) | 34.0°F (1937) | 2.70 in (1910) |
| September 17 | 95.0°F (1953) | 34.0°F (1901) | 3.18 in (1914) |
| September 18 | 93.9°F (1910) | 30.0°F (1901) | 2.88 in (1978) |
| September 19 | 95.0°F (1931) | 28.0°F (1991) | 6.35 in (2010) |
| September 20 | 93.9°F (1908) | 28.0°F (1991) | 2.99 in (1978) |
| September 21 | 96.1°F (2022) | 32.0°F (1927) | 2.40 in (1965) |
| September 22 | 99.0°F (1937) | 30.9°F (1913) | 1.93 in (2010) |
| September 23 | 90.0°F (1938) | 30.9°F (1995) | 2.25 in (1910) |
| September 24 | 93.0°F (1905) | 27.0°F (1942) | 1.55 in (1960) |
| September 25 | 89.1°F (1956) | 30.9°F (1926) | 1.90 in (1931) |
| September 26 | 91.9°F (1897) | 28.9°F (1926) | 2.92 in (1959) |
| September 27 | 98.1°F (1954) | 28.0°F (1942) | 1.75 in (1924) |
| September 28 | 99.0°F (1953) | 26.1°F (1942) | 0.86 in (2019) |
| September 29 | 91.0°F (1897) | 24.1°F (1899) | 2.06 in (1923) |
| September 30 | 91.0°F (1952) | 28.9°F (1899) | 2.10 in (1961) |