Seattle weather in September
September is one of the best months to visit Seattle: highs of 20°C (68°F) and about 58 mm (2.3 in) of rain on average. Nights average 11°C (51°F) and cloud cover 53% (NASA POWER, 2001–2025 averages). It is the 4th driest month of the year and the 3rd warmest. Compared with August, it is cooler and wetter; October brings highs of 15°C (58°F) and 125 mm (4.9 in) of rain.
Is September a good time to visit Seattle?
best month Weather score 80/100.
Yes. September is one of the best months for weather in Seattle.
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Does it rain a lot in Seattle in September?
No, it is usually dry: about 58 mm (2.3 in) falls in an average September. It is the 4th driest month of the year.
How warm is Seattle in September?
Days average 20°C (68°F) and nights 11°C (51°F).
Seattle weather by month
| Month | High | Low | Rain | Cloud | Weather |
|---|---|---|---|---|---|
| January | 7°C (45°F) | 2°C (35°F) | 174 mm | 80% | least pleasant |
| February | 8°C (46°F) | 1°C (34°F) | 108 mm | 74% | least pleasant |
| March | 10°C (51°F) | 3°C (37°F) | 138 mm | 79% | least pleasant |
| April | 13°C (56°F) | 5°C (40°F) | 95 mm | 75% | fair |
| May | 18°C (64°F) | 8°C (47°F) | 70 mm | 70% | best |
| June | 20°C (68°F) | 11°C (51°F) | 51 mm | 68% | best |
| July | 23°C (74°F) | 13°C (56°F) | 19 mm | 47% | best |
| August | 23°C (74°F) | 13°C (56°F) | 29 mm | 48% | best |
| September | 20°C (68°F) | 11°C (51°F) | 58 mm | 53% | best |
| October | 15°C (58°F) | 7°C (44°F) | 125 mm | 68% | fair |
| November | 10°C (49°F) | 4°C (38°F) | 188 mm | 77% | least pleasant |
| December | 6°C (44°F) | 1°C (34°F) | 175 mm | 79% | least pleasant |
Sources: 2001–2025 monthly averages from NASA POWER (MERRA-2 reanalysis). Page updated . How we rate months
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