The climate in Aliso Viejo during September can be summarized as warm and very dry.
September is in the fall / autumn in Aliso Viejo and is typically the 2nd warmest month of the year. Daytime maximum temperatures average around a comfortable 26°C (79°F), whilst at night 15°C (60°F) is normal.
| Daytime temperature | 26.3°C 79.3°F |
|---|---|
| Nightly temperature | 15.4°C 59.6°F |
| Average temperature | 20.8°C 69.4°F |
| Daily sunshine | 9.8 hrs |
| Avg rainfall | 5 mm 0.2 ins |
| Rainy days | 1 days |
| Sea temperature | 20.4°C 68.8°F |
| Humidity | 69% |
| Windspeed | 12.2kph 8 mph |
On average September is the 5th driest month of the year in Aliso Viejo with around 5mm 0.2 inches of rain making it a very dry time to visit.
On the flip side this corresponds to an average of 9.8 hours of sunshine per day.
The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in Aliso Viejo in September 2025.
Best places to visit in September
| Hottest month: | August | 26.4°C 79.5°F |
|---|---|---|
| Driest month: | July | 1mm 0ins |
| Sunniest month: | August | 11.4hrs |
| Coldest month: | December | 18.1°C 64.6°F |
| Wettest month: | January | 64mm 2.5ins |