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September Weather in Aliso Viejo, United States

Last updated: June 24, 2025

In Aliso Viejo, United States, the average temperature in September is a pleasant 21°C (70°F). Expect a minimum of 15°C (59°F) and a maximum of 33°C (91°F), making it an ideal time for outdoor activities. With only 3 mm (0.1 in) of precipitation over 0 days, you can look forward to mostly dry weather. The average humidity hovers around 68%, ensuring a comfortable atmosphere throughout the month.

September Temperature in Aliso Viejo

In September in Aliso Viejo, the average temperature is 21°C (70°F) with maximums reaching up to 33°C (91°F) and minimums dropping as low as 15°C (59°F). This pleasant climate makes Aliso Viejo an ideal destination for outdoor adventures and exploration during your travels.

September Weather in Aliso Viejo: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Aliso Viejo, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Aliso Viejo, September typically has an average temperature of 21°C (70°F), with highs reaching up to 33°C (91°F) and lows dropping to around 15°C (59°F).
JanFebMarAprMayJunJulAugSepOctNovDec575758616265707170686358
Data source: Temperature data for Aliso Viejo generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Aliso Viejo

In Aliso Viejo in September, the precipitation amount is 3 mm (0.1 in) during a total of 0 days.

September Precipitation Trends in Aliso Viejo

The chart displays monthly precipitation patterns in Aliso Viejo, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In Aliso Viejo, September typically receives around 3 mm (0.1 inches) of precipitation spread over approximately 0 days.
JanFebMarAprMayJunJulAugSepOctNovDec6055542514333392269
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Aliso Viejo

In Aliso Viejo in September humidity is 68%. With an average temperature of 21°C (70°F), this humidity feels like a warm embrace, making the air feel slightly heavy and sticky, which can be quite exhausting for travelers.

September Average Humidity in Aliso Viejo

This chart illustrates the average monthly humidity levels in Aliso Viejo, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in Aliso Viejo is approximately 68%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec74%79%75%71%70%72%73%69%68%67%68%71%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Aliso Viejo

In Aliso Viejo in September, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Aliso Viejo.

Maximum UV Index Levels in Aliso Viejo for September

The chart shows the monthly maximum UV Index (UVI) for Aliso Viejo in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in Aliso Viejo typically reaches 10, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec468101111111010754
Data source: Aliso Viejo September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How September Weather in Aliso Viejo Compares to Other Months

Weather in Aliso Viejo varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Aliso Viejo, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Aliso Viejo, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather14°C (58°F)60 mm (2.3 inches)74%moderate
February Weather14°C (57°F)55 mm (2.2 inches)79%high
March Weather14°C (58°F)54 mm (2.1 inches)75%very high
April Weather16°C (61°F)25 mm (1.0 inches)70%very high
May Weather16°C (62°F)14 mm (0.5 inches)70%extreme
June Weather18°C (65°F)3 mm (0.1 inches)72%extreme
July Weather21°C (70°F)3 mm (0.1 inches)73%extreme
August Weather22°C (71°F)3 mm (0.1 inches)69%very high
September Weather21°C (70°F)3 mm (0.1 inches)68%very high
October Weather20°C (68°F)9 mm (0.4 inches)67%high
November Weather17°C (63°F)22 mm (0.8 inches)68%moderate
December Weather14°C (58°F)69 mm (2.7 inches)71%moderate

Compare Aliso Viejo's Climate with Cities Worldwide