September weather in Mattawa, WA
The average temperature in Mattawa in September is 69.0°F (57.7°F–80.4°F). Average precipitation: 0.15 inches.
September is a fall month in Mattawa, and is warmer than the annual average of 56°F. Daily temperatures swing about 22.7°F between overnight low and afternoon high. Expect about 2 days with precipitation. Daylight averages about 12h 19m. For travel, September is a comfortable month to visit.
Avg High
80.4°F
Avg Low
57.7°F
Precipitation
0.15 in
Daylight
12h 19m
September records in Mattawa
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 100.9°F (1998) | 46.9°F (1980) | 0.54 in (1971) |
| September 2 | 105.1°F (1998) | 48.9°F (1973) | 0.11 in (1979) |
| September 3 | 99.0°F (1988) | 41.0°F (2000) | 0.08 in (1979) |
| September 4 | 100.9°F (2003) | 45.0°F (1980) | 0.13 in (1960) |
| September 5 | 100.0°F (1966) | 45.0°F (1961) | 0.03 in (1971) |
| September 6 | 99.0°F (1962) | 42.1°F (1961) | 0.49 in (1971) |
| September 7 | 98.1°F (1957) | 45.0°F (1992) | 0.47 in (1995) |
| September 8 | 97.0°F (2011) | 46.0°F (1962) | 0.14 in (1995) |
| September 9 | 100.9°F (2011) | 43.0°F (1962) | 0.05 in (1982) |
| September 10 | 99.0°F (2011) | 45.0°F (1982) | 0.37 in (2021) |
| September 11 | 98.1°F (1973) | 44.1°F (2012) | 0.26 in (1966) |
| September 12 | 97.0°F (2011) | 43.0°F (2012) | 0.03 in (1982) |
| September 13 | 97.0°F (2009) | 45.0°F (1970) | 0.68 in (1980) |
| September 14 | 93.9°F (1960) | 42.1°F (1962) | 0.24 in (1966) |
| September 15 | 93.0°F (1975) | 39.0°F (1970) | 0.25 in (1959) |
| September 16 | 96.1°F (1957) | 42.1°F (1992) | 0.17 in (1963) |
| September 17 | 95.0°F (1981) | 37.9°F (1965) | 0.12 in (1986) |
| September 18 | 95.0°F (1981) | 37.0°F (1965) | 0.54 in (1969) |
| September 19 | 91.9°F (1979) | 37.0°F (1957) | 0.20 in (1982) |
| September 20 | 91.9°F (1967) | 39.9°F (1985) | 0.30 in (1984) |
| September 21 | 93.9°F (1967) | 39.9°F (1988) | 0.07 in (2025) |
| September 22 | 91.0°F (1966) | 37.0°F (1981) | 0.21 in (1984) |
| September 23 | 91.0°F (2009) | 37.9°F (1993) | 0.50 in (1984) |
| September 24 | 91.0°F (2009) | 37.0°F (1958) | 0.33 in (1977) |
| September 25 | 91.9°F (2001) | 33.1°F (1996) | 0.50 in (1982) |
| September 26 | 95.0°F (1957) | 37.9°F (2000) | 0.13 in (1981) |
| September 27 | 88.0°F (1963) | 39.9°F (1996) | 0.44 in (1981) |
| September 28 | 91.9°F (1996) | 39.0°F (1985) | 0.30 in (1962) |
| September 29 | 93.0°F (1963) | 39.0°F (1971) | 0.25 in (2019) |
| September 30 | 90.0°F (1996) | 42.1°F (1985) | 0.16 in (2007) |