September weather forecast and climate
Aliso Viejo, CA

Weather in September

September, the first month of the autumn, in Aliso Viejo, is still a warm month, with average temperature fluctuating between 79.5°F (26.4°C) and 63.5°F (17.5°C).

Temperature

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

Humidity

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

Rainfall

In Aliso Viejo, in September, it is raining for 4.6 days, with typically 0.28" (7mm) of accumulated precipitation. In Aliso Viejo, during the entire year, the rain falls for 66.3 days and collects up to 5.67" (144mm) of precipitation.

Daylight

In Aliso Viejo, the average length of the day in September is 12.4h.

Sunshine

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 health risk from unsafe exposure to the UV radiation for the ordinary person.
Note: In September, the average maximum UV index of 6 translate into the following recommendations:
Take precautions against overexposure. Fair-skinned people may get burned in less than 20 minutes. The Sun's UV radiation is most powerful between 10 a.m. and 4 p.m. To the extent possible, limit exposure to the direct sun during these hours. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects.
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FAQ

What is the temperature in September in Aliso Viejo?

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 September, the average relative humidity is 64%.

How much does it rain in Aliso Viejo in September?

In Aliso Viejo, California, in September, during 4.6 rainfall days, 0.28" (7mm) of precipitation is typically accumulated.

What is the average length of the day in September in Aliso Viejo?

The average length of the day in September in Aliso Viejo, California, is 12.4h.

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

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

What are the months with the highest UV index in Aliso Viejo?

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

What is the UV index intensity in September in Aliso Viejo?

In Aliso Viejo, California, the average daily maximum UV index in September is 6. A UV Index reading of 6 to 7 represents a high hazard to health from the exposure to the Sun's UV radiation.

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"

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

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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: 12.4h

The month with the longest days is June (Average daylight: 14.4h).
The month with the shortest days is December (Average daylight: 10h).

  • Average sunshine in September: 10.5h

Months with the most sunshine are July and August (Average sunshine: 12h).
The month with the least sunshine is December (Average sunshine: 6.6h).

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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

Months with the highest UV index are June, July, August and September (UV index 6).
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

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

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

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