September weather in Portsmouth, IA
The average temperature in Portsmouth in September is 65.1°F (51.7°F–78.5°F). Average precipitation: 4.00 inches.
September is a fall month in Portsmouth, and is warmer than the annual average of 49.5°F. Daily temperatures swing about 26.8°F between overnight low and afternoon high. Expect about 7 days with precipitation. Daylight averages about 12h 16m. For travel, September is a comfortable month to visit.
Avg High
78.5°F
Avg Low
51.7°F
Precipitation
4.00 in
Daylight
12h 16m
September records in Portsmouth
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 98.1°F (1913) | 37.0°F (1949) | 2.90 in (1926) |
| September 2 | 98.1°F (1913) | 42.1°F (1924) | 3.56 in (1912) |
| September 3 | 106.0°F (2000) | 35.1°F (1974) | 1.83 in (1961) |
| September 4 | 100.0°F (1913) | 37.0°F (1902) | 3.37 in (1956) |
| September 5 | 102.0°F (1913) | 37.0°F (1962) | 3.08 in (1936) |
| September 6 | 102.9°F (1939) | 39.0°F (1988) | 2.35 in (1938) |
| September 7 | 102.0°F (1939) | 37.9°F (1934) | 2.42 in (2007) |
| September 8 | 99.0°F (2013) | 39.0°F (1986) | 6.43 in (1989) |
| September 9 | 100.0°F (1955) | 37.9°F (1916) | 2.58 in (1992) |
| September 10 | 98.1°F (1931) | 37.0°F (1929) | 3.30 in (1972) |
| September 11 | 95.0°F (1908) | 36.0°F (1955) | 7.83 in (1972) |
| September 12 | 98.1°F (1939) | 28.9°F (1902) | 4.12 in (1972) |
| September 13 | 99.0°F (1939) | 27.0°F (1902) | 7.56 in (1978) |
| September 14 | 100.0°F (1939) | 37.0°F (1929) | 1.30 in (1914) |
| September 15 | 100.9°F (1939) | 30.0°F (1916) | 3.82 in (1936) |
| September 16 | 98.1°F (1931) | 30.9°F (1903) | 2.28 in (1927) |
| September 17 | 95.0°F (1955) | 30.0°F (1900) | 0.95 in (2013) |
| September 18 | 93.9°F (1947) | 28.0°F (1901) | 2.52 in (1919) |
| September 19 | 93.9°F (1948) | 28.9°F (1991) | 1.86 in (2010) |
| September 20 | 93.0°F (1940) | 28.0°F (1918) | 1.42 in (1978) |
| September 21 | 97.0°F (1937) | 25.0°F (1918) | 1.76 in (1994) |
| September 22 | 97.0°F (1937) | 26.1°F (1913) | 1.35 in (2006) |
| September 23 | 91.9°F (1938) | 28.9°F (1983) | 2.74 in (1902) |
| September 24 | 90.0°F (1935) | 28.9°F (1942) | 1.74 in (1913) |
| September 25 | 90.0°F (1920) | 28.9°F (1907) | 1.06 in (1915) |
| September 26 | 91.9°F (1956) | 27.0°F (1926) | 5.59 in (1973) |
| September 27 | 91.0°F (1956) | 28.0°F (1928) | 2.17 in (1965) |
| September 28 | 98.1°F (1953) | 25.0°F (1942) | 1.80 in (1923) |
| September 29 | 90.0°F (1981) | 19.9°F (1899) | 2.40 in (1923) |
| September 30 | 91.0°F (1937) | 27.0°F (1899) | 3.20 in (1911) |