September weather forecast
Aliso Viejo, CA

Weather in September

The first month of the autumn, September, is also a moderately hot month in Aliso Viejo, California, with an average temperature fluctuating between 79.5°F (26.4°C) and 63.5°F (17.5°C).

Temperature

In Aliso Viejo, the average high-temperature in September is relatively the same as in August - a still warm 79.5°F (26.4°C). In September, the average low-temperature is 63.5°F (17.5°C).

Humidity

The average relative humidity in September in Aliso Viejo is 64%.

Rainfall

In Aliso Viejo, in September, during 4.6 rainfall days, 0.28" (7mm) of precipitation is typically accumulated. Throughout the year, there are 66.3 rainfall days, and 5.67" (144mm) of precipitation is accumulated.

Daylight

The average length of the day in September in Aliso Viejo, California, is 12h and 22min.
On the first day of the month, sunrise is at 6:24 am and sunset at 7:16 pm. On the last day of September, sunrise is at 6:44 am and sunset at 6:37 pm PDT.

Sunshine

In Aliso Viejo, the average sunshine in September is 10.5h.

UV index

June through September, with an average maximum UV index of 6, are months with the highest UV index. A UV Index estimate of 6 to 7 represents a high threat to health from unprotected exposure to Sun's UV rays for average individuals.
Note: In September, the average maximum UV index of 6 translate into the following recommendations:
Take precautions and adopt sun safety practices. Protection against sunburn is obliged. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. A wide-brim hat offers excellent sun protection for the eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun.
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FAQ

What is the temperature in September in Aliso Viejo?

In September, the average high-temperature is 79.5°F (26.4°C), and the average low-temperature is 63.5°F (17.5°C).

What is the average humidity in September in Aliso Viejo?

In Aliso Viejo, the average relative humidity in September is 64%.

How many days does it rain in September in Aliso Viejo?

In Aliso Viejo, in September, it is raining for 4.6 days, with typically 0.28" (7mm) of accumulated precipitation.

How many hours of daylight does Aliso Viejo have in September?

The average day length in September in Aliso Viejo is 12h and 22min.

When are sunrise and sunset in September in Aliso Viejo?

In September, on the first day of the month, sunrise is at 6:24 am and sunset at 7:16 pm. On the last day of the month, in Aliso Viejo, California, sunrise is at 6:44 am and sunset at 6:37 pm PDT.

How many hours of sunshine does Aliso Viejo have in September?

The average sunshine duration in September is 10.5h.

What is the month with the highest UV index in Aliso Viejo?

June through September, with an average maximum UV index of 6, are months with the highest UV index in Aliso Viejo, California.

How high is the UV index in September in Aliso Viejo?

The average daily maximum UV index in September is 6. A UV Index reading of 6 to 7 represents a high health threat from exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Aliso Viejo, CA

Average temperature in September - Aliso Viejo, CA
  • Average high temperature in September: 79.5°F

The warmest month (with the highest average high temperature) is August (80.2°F).
The month with the lowest average high temperature is December (62.8°F).

  • Average low temperature in September: 63.5°F

The month with the highest average low temperature is August (64.4°F).
The coldest month (with the lowest average low temperature) is February (49.6°F).

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Average pressure in September
Aliso Viejo, CA

Average pressure in September - Aliso Viejo, CA
  • Average pressure in September: 29.89"Hg

The month with the highest atmospheric pressure is January (30.09"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).

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Average wind speed in September
Aliso Viejo, CA

Average wind speed in September - Aliso Viejo, CA
  • Average wind speed in September: 4.7mph

The windiest month (with the highest average wind speed) is April (5.9mph).
The calmest months (with the lowest average wind speed) are August, September and October (4.7mph).

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Average humidity in September
Aliso Viejo, CA

Average humidity in September - Aliso Viejo, CA
  • Average humidity in September: 64%

The month with the highest relative humidity is June (71%).
The month with the lowest relative humidity is November (56%).

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Average rainfall in September
Aliso Viejo, CA

Average rainfall in September - Aliso Viejo, CA
  • Average rainfall in September: 0.28"

The wettest month (with the highest rainfall) is December (0.87").
The driest month (with the least rainfall) is June (0.08").

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Average rainfall days in September
Aliso Viejo, CA

Average rainfall days in September - Aliso Viejo, CA
  • Average rainfall days in September: 4.6 days

The month with the highest number of rainy days is March (8.3 days).
The month with the least rainy days is June (2.6 days).

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Average daylight in September /
Average sunshine in September
Aliso Viejo, CA

Average daylight in September / Average sunshine in September - Aliso Viejo, CA
  • Average daylight in September: 12h and 22min

The month with the longest days is June (Average daylight: 14h and 21min).
The month with the shortest days is December (Average daylight: 9h and 58min).

  • Average sunshine in September: 10h and 30min

The months with the most sunshine are July and August (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 6h and 36min).

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Average sunshine days in September
Aliso Viejo, CA

Average sunshine days in September - Aliso Viejo, CA
  • Average sunshine days in September: 21.7 days

The month with the most sunshine days is January (24.1 days).
The month with the least sunshine days is February (19.6 days).

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Average UV index in September
Aliso Viejo, CA

Average UV index in September - Aliso Viejo, CA
  • Average UV index in September: 6

The months with the highest UV index are June, July, August and September (UV index 6).
The months with the lowest UV index are January, February, March, November and December (UV index 4).

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Average cloud cover in September
Aliso Viejo, CA

Average cloud cover in September - Aliso Viejo, CA
  • Average cloud cover in September: 11

The months with the most cloud cover are March and December (Cloud cover 25).
The month with the least cloud cover is August (Cloud cover 7).

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Average visibility in September
Aliso Viejo, CA

Average visibility in September - Aliso Viejo, CA
  • Average visibility in September: 6mi

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

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