Rancho Cucamonga (CA)
September
Weather in Rancho Cucamonga, California for September 2026
Your guide to Rancho Cucamonga weather in September - trends and predictions
So far, September 2026 in Rancho Cucamonga is slightly warmer than the historical average by 0.8 °F.
The forecast for the upcoming days in Rancho Cucamonga predicts a temperature of 32.3 °F, which is slightly above the historical average.
In general, the average temperature in Rancho Cucamonga at the beginning of September is 34 °F. As the month progressed, temperatures tended to noticeably cool down, reaching an average of 31.9 °F by the end of September.
With an average of 3 rainy days, Rancho Cucamonga experiences minimal rainfall in September.
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Temperatures
Rain 🌧️
More
27
Dry days
3
Rainy days
0
Snow days
30°/18°
Temperatures
15 km/h
Avg max wind
49 %
Avg humidity
Rancho Cucamonga Weather September
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Temperatures trend during September in Rancho Cucamonga
See the weather trend as well as the moving average line
September weather in Rancho Cucamonga day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Sunny | 35° /19° | 0.8 mm | 9 | |
| Sept. 2 | Sunny | 34° /20° | 0.6 mm | 8 | |
| Sept. 3 | Sunny | 32° /19° | 1.4 mm | 8 | |
| Sept. 4 | Sunny | 33° /19° | 0 mm | 9 | |
| Sept. 5 |  Partly cloudy | 35° /19° | 0 mm | 9 | |
| Sept. 6 | Sunny | 33° /20° | 2.6 mm | 7 | |
| Sept. 7 | Sunny | 36° /21° | 1.1 mm | 7 | |
| Sept. 8 | Sunny | 37° /22° | 0 mm | 9 | |
| Sept. 9 | Sunny | 35° /23° | 0.4 mm | 8 | |
| Sept. 10 | Sunny | 33° /21° | 0 mm | 8 | |
| Sept. 11 | Partly cloudy | 31° /19° | 0 mm | 8 | |
| Sept. 12 | Sunny | 30° /18° | 0 mm | 8 | |
| Sept. 13 | Sunny | 29° /17° | 0 mm | 8 | |
| Sept. 14 | Sunny | 30° /17° | 0 mm | 8 | |
| Sept. 15 | Sunny | 30° /17° | 0 mm | 8 | |
| Sept. 16 | Partly cloudy | 28° /17° | 0 mm | 8 | |
| Sept. 17 | Partly cloudy | 27° /17° | 0 mm | 7 | |
| Sept. 18 |  Cloudy | 26° /17° | 0 mm | 7 | |
| Sept. 19 | Sunny | 25° /16° | 0 mm | 7 | |
| Sept. 20 | Partly cloudy | 26° /16° | 0 mm | 5 | |
| Sept. 21 | Sunny | 26° /18° | 0 mm | 7.9 | |
| Sept. 22 | Sunny | 28° /17° | 0 mm | 7.8 | |
| Sept. 23 | Sunny | 33° /21° | 0 mm | 7.7 | |
| Sept. 24 | Sunny | 32° /22° | 0.5 mm | 7.6 | |
| Sept. 25 | Sunny | 33° /22° | 0 mm | 7.5 | |
| Sept. 26 |  Overcast | 32° /24° | 0 mm | 7 | |
| Sept. 27 | Sunny | 31° /23° | 0 mm | 8 | |
| Sept. 28 | Sunny | 30° /21° | 0 mm | 8 | |
| Sept. 29 | Sunny | 33° /24° | 0 mm | 8 | |
| Sept. 30 | Sunny | 32° /23° | 0 mm | 8 | |
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Important Notice
Our weather forecast for Rancho Cucamonga 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 Rancho Cucamonga forecast closer to your planned date for the most up-to-date weather information.
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Rancho Cucamonga in September - FAQ
What are the expected maximum and minimum temperatures in Rancho Cucamonga during September?
Expect warm days with temperatures around 30°, cooling to mild conditions of 18° after sunset. Perfect for those who enjoy warm weather.
How much rainfall should be expected in Rancho Cucamonga during September?
Rainfall in Rancho Cucamonga during September is rare to nonexistent, with the total expected rainfall being less than 10 mm and approximately 3 days seeing any precipitation. Planning without the concern for rain is generally straightforward during this very dry period.
What are the typical wind conditions in Rancho Cucamonga during September?
The average wind speed in Rancho Cucamonga during September is 15 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in Rancho Cucamonga
Explore the daily rainfall trends and prepare for Rancho Cucamongas September weather 💧
Typically, Rancho Cucamonga has 3 rainy days in September with a total of 4.9 mm of rainfall.
UV exposure in Rancho Cucamonga during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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Where is Rancho Cucamonga?Get accurate weather forecasts for Rancho Cucamonga, located at latitude 34.106 and longitude -117.593. Stay updated with localized weather information tailored for Rancho Cucamonga.
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