Washington (Seattle)
September
Weather in Washington for September 2026
Your guide to Washington weather in September - trends and predictions
Until now, September 2026 in Washington is cooler than usual, with temperatures averaging 21.2 °F, this is 2.8 °F below the typical seasonal average.
The forecast for the next days in Washington predicts temperatures to be around 23 °F, close to the historical average.
In general, the average temperature in Washington at the beginning of September is 25.3 °F. As the month progressed, temperatures tended to noticeably cool down, reaching an average of 22.3 °F by the end of September.
Washington 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
Washington Weather September
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What’s the Weather Like in Washington This September?
Discover the average temperatures and weather trends across Washington’s cities this September.
Temperatures trend during September in Washington
See the weather trend as well as the moving average line
September weather in Washington day by day
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| 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 | 25° /12° | 0 mm | 5 | |
| Sept. 11 | Overcast | 20° /13° | 0.7 mm | 4 | |
| Sept. 12 |  Patchy rain possible | 21° /12° | 1.2 mm | 4 | |
| Sept. 13 | Mist | 20° /11° | 2.9 mm | 5 | |
| Sept. 14 | Patchy rain possible | 21° /10° | 2.1 mm | 4 | |
| Sept. 15 | Sunny | 20° /12° | 1.1 mm | 4.3 | |
| Sept. 16 | Sunny | 24° /11° | 0 mm | 4.6 | |
| Sept. 17 | Sunny | 25° /12° | 0 mm | 4.6 | |
| Sept. 18 | Sunny | 23° /12° | 0 mm | 4.7 | |
| Sept. 19 | Overcast | 23° /12° | 0 mm | 4.7 | |
| Sept. 20 | Overcast | 24° /12° | 0 mm | 6 | |
| Sept. 21 | Overcast | 18° /11° | 0 mm | 5 | |
| Sept. 22 | Sunny | 20° /10° | 0 mm | 6 | |
| Sept. 23 | Sunny | 23° /11° | 0 mm | 6 | |
| Sept. 24 | Overcast | 24° /13° | 0 mm | 6 | |
| Sept. 25 | Overcast | 22° /12° | 0 mm | 6 | |
| Sept. 26 | Sunny | 25° /12° | 0 mm | 6 | |
| Sept. 27 | Sunny | 25° /12° | 0 mm | 6 | |
| Sept. 28 | Sunny | 25° /12° | 0 mm | 6 | |
| 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 | |
| Next | |||||
Important Notice
Our weather forecast for Washington 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 Washington forecast closer to your planned date for the most up-to-date weather information.
Change Month
Washington in September - FAQ
What are the expected maximum and minimum temperatures in Washington 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 Washington during September?
Moderate rainfall is anticipated in Washington 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 Washington during September?
The average wind speed in Washington during September is 11 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Washington
Explore the daily rainfall trends and prepare for Washingtons September weather 💧
Typically, Washington has 6 rainy days in September with a total of 50.4 mm of rainfall.
UV exposure in Washington during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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