September weather forecast and climate
Mission Viejo, CA

The calm waters on Lake Mission Viejo, California,
The calm waters on Lake Mission Viejo, California,

Weather in September

September, the first month of the autumn, in Mission Viejo, is still a warm month, with average temperature varying between 63.3°F (17.4°C) and 79.7°F (26.5°C).

Temperature

In September, the average high-temperature is essentially the same as in August - a still moderately hot 79.7°F (26.5°C). The average low-temperature, in September, is 63.3°F (17.4°C).

Humidity

In September, the average relative humidity in Mission Viejo, California, is 63%.

Rainfall

In Mission Viejo, during September, the rain falls for 4.4 days and regularly aggregates up to 0.24" (6mm) of precipitation. In Mission Viejo, California, during the entire year, the rain falls for 64.1 days and collects up to 5.67" (144mm) of precipitation.

Daylight

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

Sunshine

In September, the average sunshine is 10.5h.

UV index

Months with the highest UV index in Mission Viejo are June through September, with an average maximum UV index of 6. A UV Index value of 6 to 7 symbolizes a high health hazard from unprotected exposure to the Sun's UV rays for the average person.
Note: The daily maximum UV index of 6 interpret into the following advice:
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 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 Mission Viejo?

In Mission Viejo, in September, the average high-temperature is 79.7°F (26.5°C), and the average low-temperature is 63.3°F (17.4°C).

What is the average humidity in September in Mission Viejo?

In Mission Viejo, California, the average relative humidity in September is 63%.

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

In Mission Viejo, during September, the rain falls for 4.4 days and regularly aggregates up to 0.24" (6mm) of precipitation.

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

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

How long on average sun shines in September in Mission Viejo?

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

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

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

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

In Mission Viejo, the average daily maximum UV index in September is 6. A UV Index value of 6 to 7 symbolizes a high health risk from unprotected exposure to the UV radiation.

Average temperature in September
Mission Viejo, CA

Average temperature in September - Mission Viejo, CA
  • Average high temperature in September: 79.7°F

The warmest month (with the highest average high temperature) is August (80.8°F).
The month with the lowest average high temperature is December (63°F).

  • Average low temperature in September: 63.3°F

The month with the highest average low temperature is August (64°F).
The coldest month (with the lowest average low temperature) is February (48.7°F).

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Average pressure in September
Mission Viejo, CA

Average pressure in September - Mission Viejo, CA
  • Average pressure in September: 29.88"

The month with the highest atmospheric pressure is January (30.1").
Months with the lowest atmospheric pressure are June and September (29.88").

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Average wind speed in September
Mission Viejo, CA

Average wind speed in September - Mission Viejo, CA
  • Average wind speed in September: 4.6mph

The windiest month (with the highest average wind speed) is April (5.8mph).
The calmest month (with the lowest average wind speed) is August (4.5mph).

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Average humidity in September
Mission Viejo, CA

Average humidity in September - Mission Viejo, CA
  • Average humidity in September: 63%

Months with the highest relative humidity are May and June (70%).
The month with the lowest relative humidity is November (56%).

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Average rainfall in September
Mission Viejo, CA

Average rainfall in September - Mission Viejo, CA
  • Average rainfall in September: 0.24"

The wettest month (with the highest rainfall) is December (0.98").
The driest month (with the least rainfall) is June (0.08").

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Average rainfall days in September
Mission Viejo, CA

Average rainfall days in September - Mission Viejo, CA
  • Average rainfall days in September: 4.4 days

The month with the highest number of rainy days is March (8.4 days).
The month with the least rainy days is June (2.3 days).

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

Average daylight in September / Average sunshine in September - Mission 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
Mission Viejo, CA

Average sunshine days in September - Mission Viejo, CA
  • Average sunshine days in September: 22.1 days

Months with the most sunshine days are January and August (24.4 days).
The month with the least sunshine days is May (19.5 days).

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Average UV index in September
Mission Viejo, CA

Average UV index in September - Mission 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
Mission Viejo, CA

Average cloud cover in September - Mission 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
Mission Viejo, CA

Average visibility in September - Mission 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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