Boise
September
Weather in Boise for September 2025
Your guide to Boise weather in September - trends and predictions
In general, the average temperature in Boise at the beginning of September is 30.9 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 27.4 °F by the end of September.
Boise sees moderate rainfall in September, averaging 6 rainy days.
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24
Dry days
6
Rainy days
0
Snow days
26°/14°
Temperatures
16 km/h
Avg max wind
35 %
Avg humidity
Boise in September average weather
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| Mon. | Tue. | Wed. | Thu. | Fri. | Sat. | Sun. |
|---|---|---|---|---|---|---|
| 1  34° | 2  30° | 3 25° | 4 29° | 5 32° | 6  33° | 7  33° |
| 8 32° | 9 31° | 10 28° | 11  22° | 12 16° | 13 20° | 14  26° |
| 15 25° | 16  19° | 17 17° | 18 17° | 19 26° | 20 25° | 21 23° |
| 22 25° | 23 24° | 24 28° | 25 31° | 26 27° | 27 28° | 28 32° |
| 29 25° | 30 21° |
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Temperatures trend during September in Boise
See the weather trend as well as the moving average line
September weather day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 | Sunny | 34° /19° | 0 mm | 8 | |
| Sept. 2 | Patchy rain possible | 30° /23° | 0.4 mm | 7 | |
| Sept. 3 | Patchy rain possible | 25° /16° | 0.2 mm | 6 | |
| Sept. 4 | Sunny | 29° /16° | 0 mm | 7 | |
| Sept. 5 | Sunny | 32° /19° | 0 mm | 8 | |
| Sept. 6 | Overcast | 33° /20° | 0 mm | 7 | |
| Sept. 7 | Partly cloudy | 33° /20° | 0 mm | 8 | |
| Sept. 8 | Patchy rain possible | 32° /22° | 1.2 mm | 7 | |
| Sept. 9 | Sunny | 31° /19° | 0 mm | 8 | |
| Sept. 10 | Overcast | 28° /19° | 0 mm | 6 | |
| Sept. 11 | Patchy light rain with thunder | 22° /12° | 2.2 mm | 5 | |
| Sept. 12 | Patchy rain possible | 16° /11° | 3.1 mm | 4 | |
| Sept. 13 | Sunny | 20° /11° | 0 mm | 6 | |
| Sept. 14 | Cloudy | 26° /16° | 0 mm | 6 | |
| Sept. 15 | Cloudy | 25° /17° | 0 mm | 6 | |
| Sept. 16 | Thundery outbreaks possible | 19° /13° | 1.1 mm | 4 | |
| Sept. 17 | Thundery outbreaks possible | 17° /10° | 15.8 mm | 4 | |
| Sept. 18 | Overcast | 17° /11° | 0 mm | 4 | |
| Sept. 19 | Partly cloudy | 26° /13° | 0 mm | 7 | |
| Sept. 20 | Sunny | 25° /11° | 0 mm | 7 | |
| Sept. 21 | Sunny | 23° /9° | 0 mm | 6 | |
| Sept. 22 | Sunny | 25° /8° | 0 mm | 7 | |
| Sept. 23 | Sunny | 24° /10° | 0 mm | 6 | |
| Sept. 24 | Sunny | 28° /12° | 0 mm | 7 | |
| Sept. 25 | Sunny | 31° /14° | 0 mm | 8 | |
| Sept. 26 | Sunny | 27° /14° | 0 mm | 7 | |
| Sept. 27 | Sunny | 28° /12° | 0 mm | 7 | |
| Sept. 28 | Sunny | 32° /14° | 0 mm | 8 | |
| Sept. 29 | Sunny | 25° /11° | 0 mm | 7 | |
| Sept. 30 | Sunny | 21° /7° | 0 mm | 6 | |
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Important Notice
Our weather forecast for Boise 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 Boise forecast closer to your planned date for the most up-to-date weather information.
Boise in September - FAQ
What are the expected maximum and minimum temperatures in Boise 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 Boise during September?
In September, Boise can expect light to moderate rainfall, totaling 24.1 mm across approximately 6 days. Occasional showers are possible, and planning ahead for them could be helpful.
What are the typical wind conditions in Boise during September?
The average wind speed in Boise during September is 16 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Boise
Explore the daily rainfall trends and prepare for Boises September weather 💧
UV exposure in Boise during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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