San Diego County (San Diego)
September
Weather in San Diego County, California for September 2026
Your guide to San Diego County weather in September - trends and predictions
Coastal Flood Advisory - See hour by hour.
Expect cooler weather in the next days in San Diego County with the forecast suggesting a temperature of 22.9 °F, lower than the historical average.
In general, the average temperature in San Diego County at the beginning of September is 27.3 °F. As the month progressed, temperatures tended to significantly cool down, reaching an average of 21.9 °F by the end of September.
Precipitation in San Diego County during September is a rare event, with an average of fewer than 2 rainy days.
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Temperatures
Rain 🌧️
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29
Dry days
1
Rainy days
0
Snow days
23°/18°
Temperatures
16 km/h
Avg max wind
74 %
Avg humidity
San Diego County Weather September
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Temperatures trend during September in San Diego County
See the weather trend as well as the moving average line
September weather in San Diego County day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Sept. 1 |  Cloudy | 26° /18° | 0 mm | 7 | |
| Sept. 2 |  Sunny | 27° /19° | 0 mm | 7 | |
| Sept. 3 | Sunny | 26° /19° | 0 mm | 8 | |
| Sept. 4 | Sunny | 26° /19° | 0 mm | 7 | |
| Sept. 5 | Sunny | 28° /19° | 0 mm | 7 | |
| Sept. 6 |  Overcast | 28° /20° | 0.1 mm | 5 | |
| Sept. 7 |  Partly cloudy | 30° /20° | 0 mm | 6 | |
| Sept. 8 | Sunny | 31° /23° | 0.2 mm | 9.5 | |
| Sept. 9 | Sunny | 26° /24° | 0.9 mm | 9.4 | |
| Sept. 10 | Sunny | 25° /22° | 0.1 mm | 9.4 | |
| Sept. 11 | Sunny | 23° /22° | 0 mm | 9.1 | |
| Sept. 12 |  Patchy rain possible | 22° /20° | 0.1 mm | 6 | |
| Sept. 13 | Sunny | 21° /20° | 0 mm | 6 | |
| Sept. 14 | Sunny | 22° /20° | 0 mm | 6 | |
| Sept. 15 | Sunny | 22° /20° | 0 mm | 6 | |
| Sept. 16 | Sunny | 22° /20° | 0 mm | 6 | |
| Sept. 17 | Sunny | 22° /20° | 0 mm | 6 | |
| Sept. 18 | Sunny | 22° /20° | 0 mm | 6 | |
| Sept. 19 | Sunny | 21° /20° | 0 mm | 6 | |
| Sept. 20 | Sunny | 21° /19° | 0 mm | 6 | |
| Sept. 21 | Sunny | 21° /19° | 0 mm | 6 | |
| Sept. 22 | Cloudy | 23° /17° | 0 mm | 5 | |
| Sept. 23 | Partly cloudy | 24° /18° | 0 mm | 6 | |
| Sept. 24 |  Mist | 23° /17° | 0 mm | 5 | |
| Sept. 25 | Mist | 23° /16° | 0 mm | 5 | |
| Sept. 26 | Overcast | 21° /16° | 0 mm | 5 | |
| Sept. 27 | Cloudy | 21° /15° | 0 mm | 5 | |
| Sept. 28 | Cloudy | 22° /16° | 0 mm | 5 | |
| Sept. 29 | Cloudy | 22° /16° | 0 mm | 5 | |
| Sept. 30 | Patchy rain possible | 21° /16° | 1.6 mm | 5 | |
| Next | |||||
Important Notice
Our weather forecast for San Diego 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 Diego County forecast closer to your planned date for the most up-to-date weather information.
Change Month
San Diego County in September - FAQ
What are the expected maximum and minimum temperatures in San Diego County during September?
During September, expect a variety of temperatures with highs around 23° and lows near 18°, suitable for diverse activities and preferences.
How much rainfall should be expected in San Diego County during September?
Rainfall in San Diego County during September is rare to nonexistent, with the total expected rainfall being less than 10 mm and approximately 1 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 San Diego County during September?
The average wind speed in San Diego County during September is 16 km/h, suggesting breezy to windy conditions, depending on your activities.
September rainfall patterns in San Diego County
Explore the daily rainfall trends and prepare for San Diego Countys September weather 💧
Typically, San Diego County has 1 rainy days in September with a total of 4.4 mm of rainfall.
UV exposure in San Diego County during September
Stay informed about UV levels for safe outdoor activities throughout the month of September ☀️
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