Seattle (WA)
September
Weather in Seattle, Washington for September 2026
Your guide to Seattle weather in September - trends and predictions
In general, the average temperature in Seattle at the beginning of September is 25.7 °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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Temperatures
Rain 🌧️
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24
Dry days
6
Rainy days
0
Snow days
22°/11°
Temperatures
11 km/h
Avg max wind
70 %
Avg humidity
Seattle Weather September
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Temperatures trend during September in Seattle
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September weather in Seattle day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Partly cloudy | 25° /12° | 0 mm | 6 | |
| Sept. 2 |  Sunny | 27° /12° | 0 mm | 7 | |
| Sept. 3 |  Overcast | 25° /13° | 0 mm | 6 | |
| Sept. 4 |  Mist | 25° /12° | 0.2 mm | 6 | |
| Sept. 5 | Overcast | 27° /14° | 0.3 mm | 7 | |
| Sept. 6 | Sunny | 26° /12° | 0.6 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 | 6 | |
| Sept. 10 |  Patchy rain possible | 25° /11° | 0 mm | 6 | |
| Sept. 11 | Overcast | 20° /13° | 0.9 mm | 5 | |
| Sept. 12 | Patchy rain possible | 21° /12° | 0.6 mm | 5 | |
| Sept. 13 | Mist | 21° /11° | 0.2 mm | 5 | |
| Sept. 14 | Patchy rain possible | 21° /10° | 2.5 mm | 5 | |
| Sept. 15 | Patchy rain possible | 21° /10° | 1.1 mm | 5 | |
| Sept. 16 | Overcast | 23° /9° | 0.5 mm | 5 | |
| Sept. 17 | Overcast | 20° /11° | 5 mm | 5 | |
| Sept. 18 | Patchy rain possible | 18° /10° | 2.2 mm | 4 | |
| Sept. 19 |  Moderate or heavy rain shower | 20° /10° | 2.9 mm | 5 | |
| Sept. 20 |  Cloudy | 21° /9° | 1 mm | 5 | |
| Sept. 21 | Partly cloudy | 21° /8° | 0.6 mm | 5 | |
| Sept. 22 | Partly cloudy | 22° /10° | 0 mm | 5 | |
| 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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Important Notice
Our weather forecast for Seattle in September is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the Seattle forecast closer to your planned date for the most up-to-date weather information.
Change Month
Seattle in September - FAQ
What are the expected maximum and minimum temperatures in Seattle during September?
Enjoy moderate daytime temperatures of up to 22° and cooler nights around 11°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Seattle during September?
Moderate rainfall is anticipated in Seattle during September, with a total of 50.4 mm spread over approximately 6 days. Considering plans for rainy days is advisable.
What are the typical wind conditions in Seattle during September?
The average wind speed in Seattle during September is 11 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Seattle
Explore the daily rainfall trends and prepare for Seattles September weather 💧
Typically, Seattle has 6 rainy days in September with a total of 50.4 mm of rainfall.
UV exposure in Seattle during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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