Weather in Tri-Cities, Washington for September 2026
Until now, September 2026 in Tri-Cities is cooler than usual, with temperatures averaging 25.7 °F, this is 4 °F below the typical seasonal average.
The forecast for the next days in Tri-Cities predicts temperatures to be around 23 °F, close to the historical average.
In general, the average temperature in Tri-Cities at the beginning of September is 32.4 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 20.3 °F by the end of September.
With an average of 5 rainy days, Tri-Cities experiences minimal rainfall in September.
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Tri-Cities Weather September
Temperatures trend during September in Tri-Cities
September weather in Tri-Cities day by day
| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Light rain | 34° /16° | 1.9 mm | 6 | |
| Sept. 2 |  Patchy rain possible | 34° /16° | 0.2 mm | 6 | |
| Sept. 3 |  Overcast | 32° /16° | 0.2 mm | 7 | |
| Sept. 4 |  Sunny | 32° /14° | 0 mm | 7 | |
| Sept. 5 | Sunny | 32° /16° | 0.3 mm | 7 | |
| Sept. 6 | Sunny | 31° /15° | 2.6 mm | 6 | |
| Sept. 7 | Sunny | 32° /16° | 0.2 mm | 7 | |
| Sept. 8 | Sunny | 32° /15° | 0 mm | 8 | |
| Sept. 9 | Sunny | 30° /15° | 0 mm | 7 | |
| Sept. 10 | Overcast | 32° /15° | 0 mm | 6 | |
| Sept. 11 | Overcast | 26° /15° | 2 mm | 5 | |
| Sept. 12 | Overcast | 28° /13° | 1.4 mm | 5 | |
| Sept. 13 | Sunny | 26° /13° | 0.9 mm | 6 | |
| Sept. 14 | Sunny | 25° /13° | 1.2 mm | 6 | |
| Sept. 15 | Sunny | 26° /12° | 0 mm | 6 | |
| Sept. 16 | Sunny | 29° /13° | 0 mm | 7 | |
| Sept. 17 | Overcast | 27° /14° | 0.1 mm | 6 | |
| Sept. 18 | Overcast | 28° /13° | 0 mm | 6 | |
| Sept. 19 | Overcast | 29° /12° | 0 mm | 7 | |
| Sept. 20 | Sunny | 26° /12° | 0.4 mm | 6 | |
| Sept. 21 | Sunny | 31° /19° | 0 mm | 4.8 | |
| Sept. 22 | Overcast | 27° /17° | 0 mm | 4.2 | |
| Sept. 23 | Overcast | 25° /14° | 0 mm | 3.9 | |
| Sept. 24 | Overcast | 25° /15° | 0 mm | 4 | |
| Sept. 25 | Sunny | 20° /13° | 1 mm | 4 | |
| Sept. 26 | Sunny | 20° /10° | 0 mm | 6 | |
| Sept. 27 | Overcast | 18° /12° | 0 mm | 5 | |
| Sept. 28 | Sunny | 20° /11° | 0 mm | 5 | |
| Sept. 29 | Sunny | 20° /11° | 0.1 mm | 6 | |
| Sept. 30 | Sunny | 19° /9° | 0 mm | 5 | |
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Tri-Cities in September - FAQ
What are the expected maximum and minimum temperatures in Tri-Cities during September?
How much rainfall should be expected in Tri-Cities during September?
What are the typical wind conditions in Tri-Cities during September?
September rainfall patterns in Tri-Cities
UV exposure in Tri-Cities during September
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Where is Tri-Cities?Get accurate weather forecasts for Tri-Cities, located at latitude 46.245 and longitude -119.196. Stay updated with localized weather information tailored for Tri-Cities.