Weather in Seattle, Washington for September 2026
Until now, September 2026 in Seattle is cooler than usual, with temperatures averaging 22 °F, this is 3.3 °F below the typical seasonal average.
Expect cooler weather in the next days in Seattle with the forecast suggesting a temperature of 23 °F, lower than the historical average.
In general, the average temperature in Seattle at the beginning of September is 25.3 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 19.3 °F by the end of September.
Seattle experiences moderate rainfall in September, with an average of 6 rainy days and a total precipitation of 50.4 mm.
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Seattle Weather September
Temperatures trend during September in Seattle
September weather in Seattle day by day
| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Partly cloudy | 25° /13° | 0 mm | 6 | |
| Sept. 2 |  Overcast | 26° /12° | 4.2 mm | 6 | |
| Sept. 3 | Overcast | 24° /12° | 0.5 mm | 5 | |
| Sept. 4 |  Mist | 25° /12° | 0.2 mm | 6 | |
| Sept. 5 | Overcast | 26° /13° | 0.2 mm | 6 | |
| Sept. 6 |  Sunny | 26° /12° | 0.5 mm | 6 | |
| Sept. 7 | Partly cloudy | 25° /12° | 0 mm | 6 | |
| Sept. 8 | Partly cloudy | 25° /12° | 0.1 mm | 6 | |
| Sept. 9 | Overcast | 24° /12° | 0 mm | 5 | |
| Sept. 10 | Overcast | 20° /14° | 0.1 mm | 1.7 | |
| Sept. 11 | Overcast | 19° /13° | 0 mm | 3.3 | |
| Sept. 12 | Overcast | 20° /12° | 0 mm | 2.8 | |
| Sept. 13 | Sunny | 20° /11° | 0 mm | 3.7 | |
| Sept. 14 | Sunny | 21° /10° | 0 mm | 6 | |
| Sept. 15 | Sunny | 25° /12° | 0 mm | 7 | |
| Sept. 16 | Sunny | 26° /13° | 0 mm | 7 | |
| Sept. 17 | Sunny | 31° /15° | 0 mm | 8 | |
| Sept. 18 | Sunny | 29° /16° | 0 mm | 7 | |
| Sept. 19 | Sunny | 22° /14° | 0 mm | 6 | |
| Sept. 20 | Sunny | 23° /12° | 0 mm | 6 | |
| Sept. 21 | Partly cloudy | 22° /12° | 0 mm | 6 | |
| Sept. 22 | Sunny | 21° /11° | 0 mm | 6 | |
| Sept. 23 | Overcast | 22° /12° | 1.2 mm | 5 | |
| Sept. 24 | Sunny | 22° /10° | 2 mm | 5 | |
| Sept. 25 | Sunny | 20° /10° | 4.6 mm | 5 | |
| Sept. 26 |  Moderate rain at times | 20° /11° | 7.4 mm | 5 | |
| Sept. 27 |  Heavy rain at times | 21° /11° | 3.7 mm | 5 | |
| Sept. 28 | Mist | 17° /10° | 4.1 mm | 4 | |
| Sept. 29 | Moderate rain at times | 17° /10° | 3.9 mm | 4 | |
| Sept. 30 | Moderate or heavy rain shower | 18° /8° | 4.7 mm | 4 | |
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Seattle in September - FAQ
What are the expected maximum and minimum temperatures in Seattle during September?
How much rainfall should be expected in Seattle during September?
What are the typical wind conditions in Seattle during September?
September rainfall patterns in Seattle
UV exposure in Seattle during September
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