Ada County (Boise)
September
Weather in Ada County, Idaho for September 2027
Your guide to Ada County weather in September - trends and predictions
In general, the average temperature in Ada County at the beginning of September is 29.2 °C. As the month progressed, temperatures tended to significantly cool down, reaching an average of 25.8 °C by the end of September.
With an average of 4 rainy days, Ada County experiences minimal rainfall in September.
Is September a good time to visit Ada County? check out the best time to travel to Ada County page.
✨ Is September a good time to visit Ada County? – Ask the AI Weatherman
Temperatures
Rain 🌧️
More
26
Dry days
4
Rainy days
0
Snow days
26°/13°
Temperatures
17 km/h
Avg max wind
38 %
Avg humidity
Ada County Weather September
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Temperatures trend during September in Ada County
See the weather trend as well as the moving average line
September weather in Ada County day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Sunny | 34° /19° | 0 mm | 7 | |
| Sept. 2 |  Patchy rain possible | 31° /19° | 0.4 mm | 7 | |
| Sept. 3 |  Light rain | 27° /17° | 9.5 mm | 5 | |
| Sept. 4 | Light rain | 26° /15° | 9.9 mm | 5 | |
| Sept. 5 | Sunny | 30° /15° | 0 mm | 7.2 | |
| Sept. 6 |  Overcast | 29° /16° | 0.3 mm | 6 | |
| Sept. 7 | Light rain | 28° /15° | 4.6 mm | 7 | |
| Sept. 8 | Patchy rain possible | 30° /15° | 0.4 mm | 6.9 | |
| Sept. 9 | Sunny | 28° /15° | 0 mm | 6 | |
| Sept. 10 | Patchy rain possible | 28° /15° | 1.7 mm | 6 | |
| Sept. 11 |  Patchy light rain with thunder | 25° /13° | 0.7 mm | 6 | |
| Sept. 12 | Patchy rain possible | 23° /12° | 1 mm | 4 | |
| Sept. 13 | Sunny | 23° /13° | 0 mm | 6 | |
| Sept. 14 |  Cloudy | 23° /13° | 0 mm | 6 | |
| Sept. 15 | Cloudy | 24° /12° | 0 mm | 6 | |
| Sept. 16 |  Thundery outbreaks possible | 24° /11° | 0.4 mm | 5 | |
| Sept. 17 | Thundery outbreaks possible | 24° /12° | 5.3 mm | 5 | |
| Sept. 18 | Patchy rain possible | 23° /14° | 2.2 mm | 4 | |
| Sept. 19 | Overcast | 27° /15° | 0 mm | 5.9 | |
| Sept. 20 | Sunny | 26° /13° | 0 mm | 5.8 | |
| Sept. 21 | Sunny | 25° /12° | 0 mm | 5 | |
| Sept. 22 | Sunny | 25° /10° | 0 mm | 5 | |
| Sept. 23 | Sunny | 26° /11° | 0 mm | 5.5 | |
| Sept. 24 | Sunny | 30° /13° | 0 mm | 5.4 | |
| Sept. 25 | Sunny | 29° /13° | 0 mm | 5.3 | |
| Sept. 26 | Sunny | 23° /10° | 0 mm | 5 | |
| Sept. 27 | Sunny | 25° /10° | 0 mm | 5 | |
| Sept. 28 | Sunny | 27° /12° | 0 mm | 5 | |
| Sept. 29 | Overcast | 23° /12° | 0 mm | 4.9 | |
| Sept. 30 | Light rain | 23° /10° | 5.2 mm | 4.9 | |
| Next | |||||
Important Notice
Our weather forecast for Ada County 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 Ada County forecast closer to your planned date for the most up-to-date weather information.
Change Month
Ada County in September - FAQ
What are the expected maximum and minimum temperatures in Ada County during September?
Enjoy moderate daytime temperatures of up to 26° and cooler nights around 13°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Ada County during September?
In September, Ada County can expect light to moderate rainfall, totaling 41.8 mm across approximately 4 days. Occasional showers are possible, and planning ahead for them could be helpful.
What are the typical wind conditions in Ada County during September?
The average wind speed in Ada County during September is 17 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Ada County
Explore the daily rainfall trends and prepare for Ada Countys September weather 💧
Typically, Ada County has 4 rainy days in September with a total of 41.8 mm of rainfall.
UV exposure in Ada County during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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