September weather in Hermiston, OR
The average temperature in Hermiston in September is 64.6°F (47.9°F–81.2°F). Average precipitation: 0.33 inches.
September is a fall month in Hermiston, and is warmer than the annual average of 53.9°F. Daily temperatures swing about 33.3°F between overnight low and afternoon high. Expect about 3 days with precipitation. Daylight averages about 12h 18m. For travel, September is a comfortable month to visit.
Avg High
81.2°F
Avg Low
47.9°F
Precipitation
0.33 in
Daylight
12h 18m
September records in Hermiston
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 100.0°F (2022) | 35.1°F (2006) | 0.01 in (2000) |
| September 2 | 99.0°F (2025) | 37.0°F (1999) | 0.09 in (2000) |
| September 3 | 99.0°F (2025) | 37.0°F (1999) | 0.00 in (1998) |
| September 4 | 98.1°F (2003) | 39.0°F (2002) | 0.05 in (2015) |
| September 5 | 97.0°F (1998) | 39.0°F (2014) | 0.22 in (2013) |
| September 6 | 99.0°F (2003) | 39.9°F (2002) | 0.36 in (2016) |
| September 7 | 95.0°F (2011) | 37.9°F (1999) | 0.13 in (2003) |
| September 8 | 95.0°F (2021) | 36.0°F (1999) | 0.59 in (2003) |
| September 9 | 96.1°F (2011) | 37.0°F (2020) | 0.05 in (2025) |
| September 10 | 93.9°F (2013) | 39.9°F (2007) | 0.27 in (2000) |
| September 11 | 95.0°F (2013) | 33.1°F (2012) | 0.41 in (2024) |
| September 12 | 95.0°F (2011) | 31.1°F (2014) | 0.00 in (1998) |
| September 13 | 93.9°F (2009) | 33.1°F (2012) | 0.10 in (2004) |
| September 14 | 95.0°F (2013) | 36.0°F (2016) | 0.13 in (2025) |
| September 15 | 97.0°F (2013) | 39.0°F (2008) | 0.90 in (2013) |
| September 16 | 93.0°F (1998) | 37.0°F (2021) | 0.06 in (2019) |
| September 17 | 91.0°F (2023) | 37.0°F (2006) | 0.43 in (2010) |
| September 18 | 91.0°F (2008) | 39.0°F (2005) | 0.22 in (1998) |
| September 19 | 91.0°F (2012) | 36.0°F (2004) | 0.25 in (2010) |
| September 20 | 91.0°F (2025) | 34.0°F (2007) | 0.28 in (2023) |
| September 21 | 90.0°F (2014) | 33.1°F (2009) | 0.20 in (2023) |
| September 22 | 91.0°F (1999) | 32.0°F (2002) | 0.08 in (2013) |
| September 23 | 91.0°F (2011) | 26.1°F (2000) | 0.04 in (2010) |
| September 24 | 91.0°F (2001) | 26.1°F (2000) | 0.06 in (2013) |
| September 25 | 91.0°F (2021) | 30.9°F (2000) | 0.06 in (2023) |
| September 26 | 89.1°F (2003) | 32.0°F (2000) | 0.07 in (2001) |
| September 27 | 88.0°F (2022) | 28.0°F (1999) | 0.55 in (2021) |
| September 28 | 88.0°F (2010) | 30.0°F (1999) | 0.12 in (2013) |
| September 29 | 87.1°F (2006) | 33.1°F (1999) | 0.12 in (2013) |
| September 30 | 84.9°F (2006) | 33.1°F (2019) | 0.30 in (2000) |