Weather in Rancho Cucamonga, California for September 2025
Beach Hazards Statement - See hour by hour.
Until now, September 2025 in Rancho Cucamonga is cooler than usual, with temperatures averaging 30.5 °F, this is -2.2 °F below the typical seasonal average.
The forecast for the next days in Rancho Cucamonga predicts temperatures to be around 33 °F, close to 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 31.6 °F by the end of September.
With an average of 4 rainy days, Rancho Cucamonga experiences minimal rainfall in September.
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Rancho Cucamonga Weather September
Temperatures trend during September in Rancho Cucamonga
September weather in Rancho Cucamonga day by day
| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Patchy rain possible | 35° /21° | 1 mm | 8 | |
| Sept. 2 |  Light rain | 34° /22° | 0.7 mm | 8 | |
| Sept. 3 | Light rain | 32° /20° | 1.8 mm | 7 | |
| Sept. 4 |  Sunny | 33° /20° | 0 mm | 8 | |
| Sept. 5 |  Partly cloudy | 34° /21° | 0 mm | 8 | |
| Sept. 6 | Sunny | 35° /20° | 0 mm | 9 | |
| Sept. 7 | Sunny | 35° /21° | 0 mm | 8 | |
| Sept. 8 | Partly cloudy | 36° /22° | 0 mm | 8 | |
| Sept. 9 | Sunny | 34° /22° | 0 mm | 8 | |
| Sept. 10 |  Overcast | 31° /20° | 0 mm | 7 | |
| Sept. 11 | Partly cloudy | 29° /18° | 0 mm | 7 | |
| Sept. 12 | Sunny | 28° /16° | 0 mm | 7 | |
| Sept. 13 | Sunny | 28° /15° | 0 mm | 7 | |
| Sept. 14 | Sunny | 30° /16° | 0 mm | 7 | |
| Sept. 15 | Sunny | 35° /20° | 0 mm | 2 | |
| Sept. 16 | Sunny | 37° /22° | 0 mm | 2 | |
| Sept. 17 | Overcast | 32° /23° | 0 mm | 1.7 | |
| Sept. 18 |  Heavy rain | 26° /21° | 51.5 mm | 1.8 | |
| Sept. 19 | Patchy rain possible | 26° /21° | 4 mm | 0 | |
| Sept. 20 | Sunny | 29° /20° | 0 mm | 6 | |
| Sept. 21 | Sunny | 34° /21° | 0 mm | 7 | |
| Sept. 22 | Sunny | 36° /23° | 0 mm | 7 | |
| Sept. 23 | Partly cloudy | 36° /24° | 0 mm | 7 | |
| Sept. 24 | Sunny | 37° /23° | 0 mm | 7 | |
| Sept. 25 | Sunny | 35° /23° | 0 mm | 7 | |
| Sept. 26 | Sunny | 32° /23° | 0 mm | 7 | |
| Sept. 27 | Sunny | 30° /21° | 0 mm | 6 | |
| Sept. 28 | Sunny | 30° /20° | 0 mm | 6 | |
| Sept. 29 | Sunny | 30° /17° | 0 mm | 8 | |
| Sept. 30 | Light rain shower | 27° /17° | 1.8 mm | 7 | |
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Rancho Cucamonga in September - FAQ
September rainfall patterns in Rancho Cucamonga
UV exposure in Rancho Cucamonga during 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.