San Bernardino County
September
Weather in San Bernardino County for September 2025
Your guide to San Bernardino County weather in September - trends and predictions
In general, the average temperature in San Bernardino County at the beginning of September is 34.6 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 31.4 °F by the end of September.
With an average of 4 rainy days, San Bernardino County experiences minimal rainfall in September, ensuring that most days remain pleasantly dry.
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26
Dry days
4
Rainy days
0
Snow days
29°/15°
Temperatures
13 km/h
Avg max wind
51 %
Avg humidity
San Bernardino County in September average weather
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| Mon. | Tue. | Wed. | Thu. | Fri. | Sat. | Sun. |
|---|---|---|---|---|---|---|
| 1  34° | 2  34° | 3 32° | 4  33° | 5 35° | 6 37° | 7  37° |
| 8 37° | 9 38° | 10  36° | 11 33° | 12 31° | 13 30° | 14 30° |
| 15 29° | 16 27° | 17 24° | 18 24° | 19 24° | 20 23° | 21 23° |
| 22  29° | 23 33° | 24 32° | 25 32° | 26 32° | 27 32° | 28 32° |
| 29 32° | 30 28° |
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Temperatures trend during September in San Bernardino County
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 | Patchy rain possible | 34° /20° | 0.6 mm | 8 | |
| Sept. 2 | Light rain | 34° /19° | 1.1 mm | 8 | |
| Sept. 3 | Light rain | 32° /16° | 2.7 mm | 8 | |
| Sept. 4 | Partly cloudy | 33° /17° | 0 mm | 8 | |
| Sept. 5 | Partly cloudy | 35° /20° | 0 mm | 9 | |
| Sept. 6 | Partly cloudy | 37° /20° | 0 mm | 9 | |
| Sept. 7 | Sunny | 37° /22° | 0.1 mm | 8 | |
| Sept. 8 | Partly cloudy | 37° /24° | 0 mm | 9 | |
| Sept. 9 | Sunny | 38° /24° | 0 mm | 9 | |
| Sept. 10 | Cloudy | 36° /23° | 0 mm | 8 | |
| Sept. 11 | Partly cloudy | 33° /21° | 0 mm | 8 | |
| Sept. 12 | Sunny | 31° /16° | 0 mm | 8 | |
| Sept. 13 | Sunny | 30° /14° | 0 mm | 8 | |
| Sept. 14 | Sunny | 30° /15° | 0 mm | 8 | |
| Sept. 15 | Partly cloudy | 29° /15° | 0 mm | 8 | |
| Sept. 16 | Sunny | 27° /14° | 0.1 mm | 7 | |
| Sept. 17 | Partly cloudy | 24° /11° | 0 mm | 6 | |
| Sept. 18 | Cloudy | 24° /13° | 0 mm | 6 | |
| Sept. 19 | Partly cloudy | 24° /12° | 0 mm | 6 | |
| Sept. 20 | Partly cloudy | 23° /12° | 0 mm | 6 | |
| Sept. 21 | Patchy rain possible | 23° /12° | 0 mm | 6 | |
| Sept. 22 | Overcast | 29° /12° | 0 mm | 7 | |
| Sept. 23 | Cloudy | 33° /16° | 0 mm | 8 | |
| Sept. 24 | Sunny | 32° /16° | 0 mm | 8 | |
| Sept. 25 | Sunny | 32° /16° | 0 mm | 8 | |
| Sept. 26 | Overcast | 32° /15° | 0 mm | 8 | |
| Sept. 27 | Partly cloudy | 32° /17° | 0 mm | 8 | |
| Sept. 28 | Sunny | 32° /16° | 0 mm | 8 | |
| Sept. 29 | Sunny | 32° /16° | 0 mm | 8 | |
| Sept. 30 | Light rain shower | 28° /15° | 1.7 mm | 7 | |
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Important Notice
Our weather forecast for San Bernardino 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 San Bernardino County forecast closer to your planned date for the most up-to-date weather information.
San Bernardino County in September - FAQ
What are the expected maximum and minimum temperatures in San Bernardino County during September?
During September, expect a variety of temperatures with highs around 29° and lows near 15°, suitable for diverse activities and preferences.
How much rainfall should be expected in San Bernardino County during September?
Expect minimal rainfall in San Bernardino County during September, with a total of 12.4 mm over approximately 4 days. This minimal precipitation is unlikely to significantly impact plans.
What are the typical wind conditions in San Bernardino County during September?
The average wind speed in San Bernardino County during September is 13 km/h, suggesting breezy to windy conditions, depending on your activities.
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Where is San Bernardino County?Get accurate weather forecasts for San Bernardino County, located at latitude 34.108 and longitude -117.29. Stay updated with localized weather information tailored for San Bernardino County.
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