Weather in Lewiston, Idaho for September 2026
Until now, September 2026 in Lewiston is cooler than usual, with temperatures averaging 23.7 °F, this is 2.9 °F below the typical seasonal average.
The forecast for the upcoming days in Lewiston predicts a temperature of 18.7 °F, which is slightly above the historical average.
In general, the average temperature in Lewiston at the beginning of September is 30.3 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 17.7 °F by the end of September.
With an average of 4 rainy days, Lewiston experiences minimal rainfall in September.
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Lewiston Weather September
Temperatures trend during September in Lewiston
September weather in Lewiston day by day
| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Sunny | 35° /17° | 0.1 mm | 5 | |
| Sept. 2 | Sunny | 31° /16° | 18.2 mm | 6 | |
| Sept. 3 | Sunny | 29° /16° | 70.6 mm | 6 | |
| Sept. 4 | Sunny | 32° /14° | 10.4 mm | 8 | |
| Sept. 5 | Sunny | 29° /12° | 0 mm | 7 | |
| Sept. 6 |  Cloudy | 29° /12° | 0.4 mm | 5 | |
| Sept. 7 |  Overcast | 27° /14° | 0.9 mm | 4 | |
| Sept. 8 |  Thundery outbreaks possible | 28° /11° | 0 mm | 6 | |
| Sept. 9 | Overcast | 28° /13° | 0 mm | 6 | |
| Sept. 10 | Overcast | 28° /15° | 0 mm | 5 | |
| Sept. 11 | Overcast | 23° /14° | 1.1 mm | 4 | |
| Sept. 12 |  Moderate rain at times | 24° /12° | 2.9 mm | 3 | |
| Sept. 13 |  Partly cloudy | 23° /10° | 6.2 mm | 5 | |
| Sept. 14 | Partly cloudy | 21° /11° | 4.9 mm | 4 | |
| Sept. 15 | Overcast | 20° /10° | 0 mm | 4 | |
| Sept. 16 | Sunny | 25° /10° | 0.3 mm | 6 | |
| Sept. 17 | Moderate or heavy rain shower | 24° /12° | 0.6 mm | 5 | |
| Sept. 18 | Overcast | 26° /12° | 0 mm | 6 | |
| Sept. 19 | Sunny | 28° /13° | 0 mm | 6 | |
| Sept. 20 | Sunny | 26° /12° | 0 mm | 6 | |
| Sept. 21 | Overcast | 23° /11° | 0 mm | 5 | |
| Sept. 22 | Cloudy | 23° /11° | 0 mm | 4 | |
| Sept. 23 | Overcast | 21° /11° | 0 mm | 4.2 | |
| Sept. 24 | Overcast | 25° /13° | 0 mm | 4.5 | |
| Sept. 25 | Sunny | 19° /12° | 1 mm | 3.7 | |
| Sept. 26 | Overcast | 16° /7° | 0 mm | 4.2 | |
| Sept. 27 | Overcast | 13° /8° | 1.5 mm | 3 | |
| Sept. 28 |  Patchy rain possible | 14° /8° | 0.6 mm | 3 | |
| Sept. 29 | Sunny | 16° /7° | 0 mm | 4 | |
| Sept. 30 | Overcast | 21° /11° | 0 mm | 6 | |
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Lewiston in September - FAQ
What are the expected maximum and minimum temperatures in Lewiston during September?
How much rainfall should be expected in Lewiston during September?
What are the typical wind conditions in Lewiston during September?
September rainfall patterns in Lewiston
UV exposure in Lewiston during September
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Where is Lewiston?Get accurate weather forecasts for Lewiston, located at latitude 46.417 and longitude -117.018. Stay updated with localized weather information tailored for Lewiston.