Lewiston (ID)
September
Weather in Lewiston, Idaho for September 2026
Your guide to Lewiston weather in September - trends and predictions
In general, the average temperature in Lewiston at the beginning of September is 36.3 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 25.1 °F by the end of September.
With an average of 5 rainy days, Lewiston experiences minimal rainfall in September.
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Temperatures
Rain 🌧️
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25
Dry days
5
Rainy days
0
Snow days
27°/13°
Temperatures
15 km/h
Avg max wind
45 %
Avg humidity
Lewiston Weather September
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Temperatures trend during September in Lewiston
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September weather in Lewiston day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Sunny | 39° /19° | 0 mm | 9 | |
| Sept. 2 | Sunny | 39° /20° | 0 mm | 9 | |
| Sept. 3 | Sunny | 40° /20° | 0 mm | 10 | |
| Sept. 4 | Sunny | 39° /20° | 0 mm | 9 | |
| Sept. 5 | Sunny | 32° /14° | 0 mm | 8 | |
| Sept. 6 |  Cloudy | 34° /15° | 0 mm | 7 | |
| Sept. 7 |  Overcast | 31° /17° | 0 mm | 7 | |
| Sept. 8 |  Thundery outbreaks possible | 29° /13° | 0 mm | 6 | |
| Sept. 9 | Sunny | 28° /14° | 0 mm | 7 | |
| Sept. 10 | Overcast | 27° /16° | 0 mm | 6 | |
| Sept. 11 |  Heavy rain at times | 21° /13° | 1.5 mm | 5 | |
| Sept. 12 |  Moderate rain at times | 21° /13° | 4.3 mm | 5 | |
| Sept. 13 |  Partly cloudy | 27° /11° | 0 mm | 7 | |
| Sept. 14 | Partly cloudy | 22° /12° | 5.1 mm | 5 | |
| Sept. 15 | Overcast | 21° /11° | 0.1 mm | 6 | |
| Sept. 16 |  Patchy rain possible | 25° /10° | 0.4 mm | 6 | |
| Sept. 17 | Moderate or heavy rain shower | 25° /12° | 0.9 mm | 6 | |
| Sept. 18 | Overcast | 27° /13° | 0 mm | 7 | |
| Sept. 19 | Sunny | 29° /14° | 0 mm | 7 | |
| Sept. 20 | Sunny | 27° /12° | 0 mm | 7 | |
| Sept. 21 | Overcast | 21° /10° | 0 mm | 5 | |
| Sept. 22 | Cloudy | 22° /8° | 0 mm | 6 | |
| Sept. 23 | Sunny | 27° /10° | 0 mm | 7 | |
| Sept. 24 | Sunny | 31° /11° | 0 mm | 8 | |
| Sept. 25 | Patchy rain possible | 31° /13° | 1.9 mm | 8 | |
| Sept. 26 | Partly cloudy | 20° /9° | 0.1 mm | 6 | |
| Sept. 27 | Sunny | 27° /8° | 0 mm | 7 | |
| Sept. 28 | Sunny | 27° /10° | 0 mm | 7 | |
| Sept. 29 | Patchy rain possible | 21° /9° | 0.1 mm | 5 | |
| Sept. 30 | Sunny | 19° /5° | 0 mm | 5 | |
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Important Notice
Our weather forecast for Lewiston 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 Lewiston forecast closer to your planned date for the most up-to-date weather information.
Change Month
Lewiston in September - FAQ
What are the expected maximum and minimum temperatures in Lewiston during September?
Enjoy moderate daytime temperatures of up to 27° and cooler nights around 13°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Lewiston during September?
Expect minimal rainfall in Lewiston during September, with a total of 10.7 mm over approximately 5 days. This minimal precipitation is unlikely to significantly impact plans.
What are the typical wind conditions in Lewiston during September?
The average wind speed in Lewiston during September is 15 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Lewiston
Explore the daily rainfall trends and prepare for Lewistons September weather 💧
UV exposure in Lewiston during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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