September weather in Friday Harbor, WA
The average temperature in Friday Harbor in September is 58.0°F (47.9°F–68.1°F). Average precipitation: 1.04 inches.
September is a fall month in Friday Harbor, and is warmer than the annual average of 50.9°F. Daily temperatures swing about 20.2°F between overnight low and afternoon high. Expect about 12 days with precipitation. Daylight averages about 12h 20m. For travel, September is a comfortable month to visit.
Avg High
68.1°F
Avg Low
47.9°F
Precipitation
1.04 in
Daylight
12h 20m
September records in Friday Harbor
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 81.0°F (2024) | 41.0°F (1999) | 0.26 in (2004) |
| September 2 | 84.0°F (2006) | 39.9°F (1999) | 0.32 in (2014) |
| September 3 | 89.1°F (2017) | 43.0°F (1999) | 0.05 in (2009) |
| September 4 | 87.1°F (2017) | 42.1°F (2002) | 0.05 in (2013) |
| September 5 | 84.9°F (2024) | 41.0°F (2002) | 0.11 in (2009) |
| September 6 | 84.9°F (2024) | 41.0°F (2002) | 0.42 in (2010) |
| September 7 | 82.0°F (2012) | 39.9°F (1999) | 0.31 in (2003) |
| September 8 | 84.0°F (2011) | 44.1°F (2001) | 0.10 in (2000) |
| September 9 | 82.9°F (2020) | 42.1°F (1998) | 0.30 in (2006) |
| September 10 | 86.0°F (2020) | 41.0°F (1999) | 0.30 in (2004) |
| September 11 | 84.9°F (2013) | 41.0°F (2000) | 0.04 in (2010) |
| September 12 | 78.1°F (2009) | 39.9°F (2012) | 0.47 in (2019) |
| September 13 | 80.1°F (1999) | 41.0°F (2003) | 0.16 in (2004) |
| September 14 | 78.1°F (2014) | 44.1°F (2003) | 0.38 in (2004) |
| September 15 | 81.0°F (2014) | 0.1°F (2014) | 0.35 in (2019) |
| September 16 | 81.0°F (2025) | 41.0°F (1999) | 0.39 in (2010) |
| September 17 | 78.1°F (2012) | 41.0°F (2002) | 0.53 in (2021) |
| September 18 | 75.0°F (2009) | 41.0°F (2005) | 0.42 in (2010) |
| September 19 | 79.0°F (1999) | 43.0°F (1998) | 0.34 in (2009) |
| September 20 | 77.0°F (2022) | 39.9°F (2002) | 0.27 in (2008) |
| September 21 | 75.9°F (2022) | 39.0°F (2002) | 0.14 in (2001) |
| September 22 | 78.1°F (2009) | 37.9°F (2000) | 0.37 in (2004) |
| September 23 | 75.9°F (2011) | 36.0°F (2000) | 0.48 in (2020) |
| September 24 | 73.0°F (2024) | 39.0°F (2000) | 0.56 in (2013) |
| September 25 | 73.9°F (2022) | 39.0°F (2000) | 0.53 in (2024) |
| September 26 | 75.9°F (2022) | 39.9°F (2000) | 0.49 in (2010) |
| September 27 | 77.0°F (2003) | 39.0°F (1999) | 0.24 in (2019) |
| September 28 | 81.0°F (2003) | 37.9°F (1999) | 0.58 in (2013) |
| September 29 | 73.9°F (2018) | 39.9°F (1999) | 0.53 in (2005) |
| September 30 | 72.0°F (2020) | 37.9°F (1999) | 0.38 in (2021) |