Seattle, Washington Weather in September
United States · September climate averages and travel tips
Avg high21°C (69°F)
Avg low11°C (52°F)
Rainfall62 mm (2.4 in)
RatingExcellent 9.8/10
In September, Seattle has average highs of 21°C (69°F) and lows of 11°C (52°F). September is autumn (fall) in United States. The month is moderately rainy, with about 62 mm (2.4 in) of rain spread over 9 days. You get roughly 12.3 hours of daylight and a mix of sun and cloud.
Is September a good time to visit Seattle?
Yes — September is one of the best months to visit Seattle. The weather rates excellent (9.8/10) on our comfort score.
September weather at a glance
| Average high | 21°C (69°F) |
|---|---|
| Average low | 11°C (52°F) |
| Daily mean | 15°C (60°F) |
| Rainfall | 62 mm (2.4 in) |
| Rainy days (1 mm+) | 9 |
| Humidity | 79% |
| Cloud cover | 54% |
| Daylight | 12.3 hours |
| Est. sunshine | 6.2 hours/day |
| Wind | 2.2 km/h |
| vs August | 3°C cooler than August, with 37 mm more rain. |
What to pack for Seattle in September
- T-shirts plus a light layer for the evening
- a sweater for cool nights
Seattle weather in other months
Jan7°C / 2°C178 mmPoorFeb8°C / 2°C117 mmPoorMar11°C / 3°C133 mmPoorApr13°C / 5°C98 mmPoorMay18°C / 8°C73 mmGoodJun20°C / 11°C57 mmExcellentJul23°C / 13°C19 mmExcellentAug24°C / 13°C25 mmExcellentSep21°C / 11°C62 mmExcellentOct15°C / 8°C125 mmFairNov10°C / 4°C196 mmPoorDec7°C / 2°C184 mmPoor
← AugustBest time to visit SeattleOctober →
Nearby in September
- Victoria18°C · 53 mm
- Vancouver18°C · 74 mm
- Calgary20°C · 49 mm
- Edmonton19°C · 41 mm
- San Francisco, California24°C · 4 mm
- Las Vegas, Nevada36°C · 10 mm
Where else is good in September? See where to go in September.