Idaho (Boise)
September
Weather in Idaho for September 2025
Your guide to Idaho weather in September - trends and predictions
Until now, September 2025 in Idaho has been nearly identical to the historical average, with a temperature of 29.5 °F (showing only a slight deviation of 0.5 °F).
The forecast for the next days in Idaho predicts a temperature of 22.9 °F, which is cooler than the historical average.
In general, the average temperature in Idaho at the beginning of September is 32 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 17.9 °F by the end of September.
With an average of 5 rainy days, Idaho experiences minimal rainfall in September.
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Temperatures
Rain 🌧️
More
25
Dry days
5
Rainy days
0
Snow days
26°/14°
Temperatures
16 km/h
Avg max wind
34 %
Avg humidity
Idaho Weather September
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What’s the Weather Like in Idaho This September?
Discover the average temperatures and weather trends across Idaho’s cities this September.
Temperatures trend during September in Idaho
See the weather trend as well as the moving average line
September weather in Idaho day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Sunny | 35° /18° | 0 mm | 9 | |
| Sept. 2 |  Patchy rain possible | 33° /20° | 0.2 mm | 8 | |
| Sept. 3 | Patchy rain possible | 30° /18° | 0.1 mm | 7 | |
| Sept. 4 | Sunny | 31° /17° | 0 mm | 7 | |
| Sept. 5 | Sunny | 32° /19° | 0 mm | 8 | |
| Sept. 6 |  Overcast | 32° /18° | 0 mm | 7 | |
| Sept. 7 |  Partly cloudy | 31° /18° | 0 mm | 7 | |
| Sept. 8 | Patchy rain possible | 31° /18° | 0.6 mm | 8 | |
| Sept. 9 | Sunny | 28° /17° | 0 mm | 7 | |
| Sept. 10 | Overcast | 27° /16° | 2.6 mm | 6 | |
| Sept. 11 |  Patchy light rain with thunder | 24° /13° | 1.1 mm | 6 | |
| Sept. 12 | Patchy rain possible | 19° /12° | 1.5 mm | 5 | |
| Sept. 13 | Sunny | 23° /13° | 0 mm | 7 | |
| Sept. 14 |  Cloudy | 25° /15° | 0 mm | 6 | |
| Sept. 15 | Partly cloudy | 24° /8° | 0 mm | 1.4 | |
| Sept. 16 | Sunny | 27° /11° | 0 mm | 1.4 | |
| Sept. 17 | Sunny | 28° /12° | 0 mm | 1.5 | |
| Sept. 18 | Sunny | 29° /17° | 0 mm | 1.5 | |
| Sept. 19 | Partly cloudy | 29° /19° | 0 mm | 0 | |
| Sept. 20 | Sunny | 29° /19° | 0 mm | 6 | |
| Sept. 21 | Patchy rain possible | 25° /17° | 0.3 mm | 5 | |
| Sept. 22 | Sunny | 23° /15° | 0 mm | 5 | |
| Sept. 23 | Sunny | 27° /18° | 0 mm | 6 | |
| Sept. 24 | Sunny | 27° /14° | 0.1 mm | 6 | |
| Sept. 25 | Patchy rain possible | 18° /12° | 0.2 mm | 4 | |
| Sept. 26 | Patchy rain possible | 16° /10° | 0.6 mm | 3 | |
| Sept. 27 | Patchy rain possible | 8° /5° | 4.1 mm | 2 | |
| Sept. 28 | Patchy rain possible | 10° /5° | 0.7 mm | 2 | |
| Sept. 29 | Sunny | 25° /11° | 0 mm | 7 | |
| Sept. 30 | Sunny | 21° /7° | 0 mm | 6 | |
| Next | |||||
Important Notice
Our weather forecast for Idaho 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 Idaho forecast closer to your planned date for the most up-to-date weather information.
Change Month
Idaho in September - FAQ
What are the expected maximum and minimum temperatures in Idaho during September?
Enjoy moderate daytime temperatures of up to 26° and cooler nights around 14°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Idaho during September?
In September, Idaho can expect light to moderate rainfall, totaling 24.1 mm across approximately 5 days. Occasional showers are possible, and planning ahead for them could be helpful.
What are the typical wind conditions in Idaho during September?
The average wind speed in Idaho during September is 16 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Idaho
Explore the daily rainfall trends and prepare for Idahos September weather 💧
UV exposure in Idaho during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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Top locations in Idaho
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