Seattle Weather in September
Typical September in Seattle: days around 72°F, nights around 54°F — based on 30-year climate normals (NOAA, 1991–2020), day by day below.
72°Faverage high
54°Faverage low
75°Fwarmest normal day
67°Fcoolest normal day
Day-by-day September normals for Seattle
Long-term daily averages (NOAA 1991–2020) — climate, not a live forecast. For the next 16 days, use the live forecast.
| Day | Avg high | Avg low |
|---|---|---|
| Sep 1 | 75°F | 56°F |
| Sep 2 | 75°F | 56°F |
| Sep 3 | 75°F | 56°F |
| Sep 4 | 75°F | 56°F |
| Sep 5 | 75°F | 55°F |
| Sep 6 | 74°F | 55°F |
| Sep 7 | 74°F | 55°F |
| Sep 8 | 74°F | 55°F |
| Sep 9 | 74°F | 55°F |
| Sep 10 | 74°F | 55°F |
| Sep 11 | 73°F | 54°F |
| Sep 12 | 73°F | 54°F |
| Sep 13 | 73°F | 54°F |
| Sep 14 | 72°F | 54°F |
| Sep 15 | 72°F | 54°F |
| Sep 16 | 72°F | 54°F |
| Sep 17 | 72°F | 54°F |
| Sep 18 | 71°F | 53°F |
| Sep 19 | 71°F | 53°F |
| Sep 20 | 70°F | 53°F |
| Sep 21 | 70°F | 53°F |
| Sep 22 | 70°F | 52°F |
| Sep 23 | 69°F | 52°F |
| Sep 24 | 69°F | 52°F |
| Sep 25 | 69°F | 52°F |
| Sep 26 | 68°F | 52°F |
| Sep 27 | 68°F | 51°F |
| Sep 28 | 68°F | 51°F |
| Sep 29 | 67°F | 51°F |
| Sep 30 | 67°F | 51°F |
September in Seattle through the years
Real photos taken in Seattle in September by Weathershot app users — different years, same month.
More months: October · Live Seattle forecast
Climate normals: NOAA 1991–2020 (GHCND). Photos: Weathershot community, taken on location. © Weathershot · Byss Mobile