September weather in Rock Island, WA
The average temperature in Rock Island in September is 64.6°F (52.5°F–76.7°F). Average precipitation: 0.23 inches.
September is a fall month in Rock Island, and is warmer than the annual average of 51.2°F. Daily temperatures swing about 24.2°F between overnight low and afternoon high. Expect about 3 days with precipitation. Daylight averages about 12h 19m. For travel, September is one of the best months of the year to visit.
Avg High
76.7°F
Avg Low
52.5°F
Precipitation
0.23 in
Daylight
12h 19m
September records in Rock Island
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 100.9°F (1987) | 44.1°F (1964) | 0.31 in (1971) |
| September 2 | 100.0°F (1998) | 44.1°F (1960) | 0.03 in (2000) |
| September 3 | 99.0°F (2025) | 46.0°F (1980) | 0.22 in (1997) |
| September 4 | 97.0°F (1988) | 44.1°F (1996) | 0.14 in (1960) |
| September 5 | 97.0°F (1990) | 46.9°F (1997) | 0.27 in (2013) |
| September 6 | 97.0°F (2020) | 44.1°F (1960) | 0.38 in (2015) |
| September 7 | 93.0°F (1963) | 42.1°F (1992) | 0.59 in (1995) |
| September 8 | 93.0°F (1993) | 43.0°F (2000) | 0.23 in (1985) |
| September 9 | 97.0°F (2011) | 41.0°F (2000) | 0.06 in (1985) |
| September 10 | 96.1°F (2011) | 44.1°F (1972) | 0.21 in (2021) |
| September 11 | 93.9°F (1973) | 44.1°F (1964) | 0.37 in (1966) |
| September 12 | 97.0°F (2011) | 39.9°F (1962) | 0.02 in (2022) |
| September 13 | 97.0°F (2013) | 37.9°F (1970) | 1.13 in (1980) |
| September 14 | 93.0°F (2013) | 41.0°F (1986) | 0.08 in (1996) |
| September 15 | 91.9°F (1995) | 39.9°F (1969) | 0.32 in (2013) |
| September 16 | 91.9°F (1981) | 39.0°F (1973) | 0.81 in (1986) |
| September 17 | 93.0°F (1981) | 39.0°F (1965) | 0.42 in (1986) |
| September 18 | 90.0°F (1967) | 41.0°F (1971) | 0.57 in (1986) |
| September 19 | 90.0°F (1967) | 37.0°F (1983) | 0.44 in (2010) |
| September 20 | 91.0°F (1967) | 33.1°F (1983) | 0.08 in (1972) |
| September 21 | 91.9°F (1967) | 37.9°F (1983) | 0.06 in (2000) |
| September 22 | 90.0°F (1966) | 37.9°F (2000) | 1.36 in (1984) |
| September 23 | 90.0°F (1974) | 33.1°F (2000) | 0.30 in (1977) |
| September 24 | 90.0°F (2009) | 37.0°F (2000) | 0.09 in (1982) |
| September 25 | 87.1°F (1962) | 34.0°F (1972) | 0.36 in (1977) |
| September 26 | 86.0°F (1962) | 37.0°F (1972) | 0.09 in (1981) |
| September 27 | 88.0°F (1963) | 32.0°F (1972) | 0.07 in (1995) |
| September 28 | 89.1°F (1963) | 34.0°F (1999) | 0.28 in (1977) |
| September 29 | 87.1°F (1976) | 30.9°F (1985) | 0.08 in (1971) |
| September 30 | 84.9°F (1970) | 34.0°F (1985) | 0.11 in (2007) |