September weather in DuPont, WA
The average temperature in DuPont in September is 60.5°F (51.4°F–69.6°F). Average precipitation: 1.54 inches.
September is a fall month in DuPont, and is warmer than the annual average of 51.9°F. Daily temperatures swing about 18.2°F between overnight low and afternoon high. Expect about 9 days with precipitation. Daylight averages about 12h 19m. For travel, September is one of the best months of the year to visit.
Avg High
69.6°F
Avg Low
51.4°F
Precipitation
1.54 in
Daylight
12h 19m
September records in DuPont
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 84.9°F (2024) | 45.0°F (2021) | 0.44 in (2015) |
| September 2 | 88.0°F (2006) | 46.0°F (1999) | 0.07 in (2000) |
| September 3 | 86.0°F (2003) | 48.9°F (1999) | 0.70 in (2007) |
| September 4 | 88.0°F (2003) | 45.0°F (2000) | 0.43 in (2007) |
| September 5 | 89.1°F (2024) | 48.0°F (2002) | 0.26 in (2009) |
| September 6 | 87.1°F (2024) | 48.9°F (2002) | 0.42 in (2016) |
| September 7 | 86.0°F (2012) | 48.9°F (1999) | 0.18 in (2009) |
| September 8 | 82.0°F (1999) | 48.9°F (2001) | 0.49 in (2010) |
| September 9 | 84.0°F (2020) | 48.9°F (2016) | 0.22 in (2019) |
| September 10 | 88.0°F (2020) | 48.0°F (1999) | 0.61 in (2004) |
| September 11 | 88.0°F (2013) | 46.9°F (2000) | 0.53 in (2024) |
| September 12 | 84.0°F (2009) | 48.9°F (2000) | 0.26 in (2004) |
| September 13 | 84.0°F (1999) | 46.9°F (2020) | 0.34 in (2004) |
| September 14 | 82.9°F (2014) | 48.0°F (2016) | 0.48 in (2024) |
| September 15 | 84.9°F (2014) | 45.0°F (2017) | 0.25 in (2019) |
| September 16 | 90.0°F (2025) | 43.0°F (2021) | 0.84 in (2010) |
| September 17 | 78.1°F (2025) | 46.0°F (2003) | 1.48 in (2010) |
| September 18 | 80.1°F (2012) | 44.1°F (2018) | 1.15 in (2010) |
| September 19 | 81.0°F (1999) | 46.0°F (2018) | 0.26 in (2010) |
| September 20 | 77.0°F (1999) | 46.9°F (2002) | 0.27 in (2017) |
| September 21 | 78.1°F (2022) | 46.0°F (2023) | 0.23 in (2025) |
| September 22 | 84.0°F (2009) | 45.0°F (2005) | 0.22 in (2019) |
| September 23 | 81.0°F (2009) | 41.0°F (2000) | 1.00 in (2020) |
| September 24 | 78.1°F (2024) | 41.0°F (2000) | 0.69 in (2014) |
| September 25 | 77.0°F (2006) | 42.1°F (2000) | 0.56 in (2020) |
| September 26 | 82.9°F (2022) | 42.1°F (2000) | 0.68 in (2011) |
| September 27 | 78.1°F (2003) | 42.1°F (2000) | 0.58 in (2023) |
| September 28 | 82.9°F (2017) | 44.1°F (1999) | 0.35 in (2007) |
| September 29 | 75.0°F (2008) | 44.1°F (2016) | 0.68 in (2005) |
| September 30 | 72.0°F (2020) | 39.9°F (2019) | 0.78 in (2007) |