Seattle in September
7.9out of 10
Yes, a good time to go
Mild: highs around 22°C. Some rain: about 8 rainy days.
22°CAvg high
12°CAvg low
8Rainy days (67 mm)
12:19 hDaylight
06:54Sunrise · 19:13 Sunset
Why this score
- Mild: highs around 22°C
- Some rain: about 8 rainy days
What to wear and pack
- Layers you can add or remove
- A light jacket for cooler evenings
- Rain jacket or compact umbrella
How reliable is the forecast?
Rain in September varies a lot between years (±3.9 rainy days), so check the forecast closer to your trip. Averages cover 30 years (1991–2020). Individual days can differ a lot.
Year at a glance
Weather by month
| Month | Avg high | Avg low | Rainfall | Rainy days | Humidity | Sunshine | Score |
|---|---|---|---|---|---|---|---|
| January | 8°C | 4°C | 176 mm | 18 | – | – | 4.0 |
| February | 10°C | 4°C | 122 mm | 14 | – | – | 5.0 |
| March | 12°C | 5°C | 139 mm | 17 | – | – | 4.9 |
| April | 15°C | 7°C | 114 mm | 16 | – | – | 5.6 |
| May | 18°C | 10°C | 76 mm | 13 | – | – | 6.8 |
| June | 21°C | 12°C | 60 mm | 10 | – | – | 7.6 |
| July | 25°C | 14°C | 25 mm | 5 | – | – | 8.4 |
| August | 25°C | 14°C | 32 mm | 5 | – | – | 8.4 |
| September | 22°C | 12°C | 67 mm | 8 | – | – | 7.9 |
| October | 16°C | 9°C | 134 mm | 15 | – | – | 5.9 |
| November | 11°C | 6°C | 192 mm | 18 | – | – | 4.3 |
| December | 8°C | 4°C | 178 mm | 18 | – | – | 4.0 |
Frequently asked questions
How hot is Seattle in September?
Daytime highs average 22°C and nights about 12°C.
When is the best time to visit Seattle?
The best months are July, August, September.