September weather forecast and climate
San Clemente, CA

Weather in September

The first month of the autumn, September, is also a moderately hot month in San Clemente, California, with average temperature varying between 63.5°F (17.5°C) and 77.4°F (25.2°C).

Temperature

The warmest month is September, with an average high-temperature of 77.4°F (25.2°C) and an average low-temperature of 63.5°F (17.5°C).

Humidity

In San Clemente, the average relative humidity is 68%.

Rainfall

In San Clemente, it is raining for 3.3 days, with typically 0.12" (3mm) of accumulated precipitation. Throughout the year, in San Clemente, there are 51.1 rainfall days, and 3.66" (93mm) of precipitation is accumulated.

Ocean temperature

In San Clemente, the average seawater temperature in September is 67.1°F (19.5°C).
Note: For most, swimming in 67.1°F (19.5°C) is not an enjoyable activity. Furthermore, controlling your breathing becomes progressively more difficult as the water temperature decreases from 69.8°F (21°C) to 59°F (15°C).

Daylight

In San Clemente, the average length of the day in September is 12.4h.

Sunshine

In San Clemente, the average sunshine is 10.2h.

UV index

July through September, with an average maximum UV index of 6, are months with the highest UV index. A UV Index of 6 to 7 symbolizes a high health risk from the exposure to the Sun's UV radiation for ordinary individuals.
Note: In September, the average maximum UV index of 6 translate into the following recommendations:
Take precautions and utilize sun safety practices. Protection against the skin and eye damage is required. 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 warmest month in San Clemente?

The warmest month in San Clemente, California, is September, with an average high-temperature of 77.4°F (25.2°C) and an average low-temperature of 63.5°F (17.5°C).

What is the temperature in September in San Clemente?

The average high-temperature, in September, in San Clemente, is 77.4°F (25.2°C), while the average low-temperature is 63.5°F (17.5°C).

What is the average humidity in September in San Clemente?

In San Clemente, California, the average relative humidity in September is 68%.

How much does it rain in San Clemente in September?

In San Clemente, California, in September, it is raining for 3.3 days, with typically 0.12" (3mm) of accumulated precipitation.

How cold is the water in September in San Clemente?

In San Clemente, California, in September, the average water temperature is 67.1°F (19.5°C). For most, swimming in 67.1°F (19.5°C) is not an enjoyable activity. Furthermore, controlling your breathing becomes progressively more difficult as the water temperature decreases from 69.8°F (21°C) to 59°F (15°C).

How many hours of daylight does San Clemente have in September?

In September, the average length of the day in San Clemente is 12.4h.

How long on average sun shines in September in San Clemente?

The average sunshine in September in San Clemente is 10.2h.

What are the months with the highest UV index in San Clemente?

July through September, with an average maximum UV index of 6, are months with the highest UV index in San Clemente, California.

How high is the UV index in September in San Clemente?

In September, the average daily maximum UV index in San Clemente is 6. A UV Index estimate of 6 to 7 represents a high health vulnerability from the exposure to the Sun's UV radiation.

Average temperature in September
San Clemente, CA

Average temperature in September - San Clemente, CA
  • Average high temperature in September: 77.4°F

The warmest month (with the highest average high temperature) is September (77.4°F).
The month with the lowest average high temperature is December (62.6°F).

  • Average low temperature in September: 63.5°F

Months with the highest average low temperature are August and September (63.5°F).
The coldest month (with the lowest average low temperature) is February (49.6°F).

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Average pressure in September
San Clemente, CA

Average pressure in September - San Clemente, 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
San Clemente, CA

Average wind speed in September - San Clemente, CA
  • Average wind speed in September: 4.9mph

The windiest month (with the highest average wind speed) is April (6.2mph).
The calmest months (with the lowest average wind speed) are August and September (4.9mph).

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Average humidity in September
San Clemente, CA

Average humidity in September - San Clemente, CA
  • Average humidity in September: 68%

The month with the highest relative humidity is June (75%).
The month with the lowest relative humidity is November (60%).

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Average rainfall in September
San Clemente, CA

Average rainfall in September - San Clemente, CA
  • Average rainfall in September: 0.12"

The wettest month (with the highest rainfall) is December (0.71").
The driest month (with the least rainfall) is June (0.08").

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Average rainfall days in September
San Clemente, CA

Average rainfall days in September - San Clemente, CA
  • Average rainfall days in September: 3.3 days

The month with the highest number of rainy days is March (7.3 days).
The month with the least rainy days is June (1.4 days).

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Average sea temperature in September
San Clemente, CA

Average sea temperature in September - San Clemente, CA
  • Average sea temperature in September: 67.1°F

The best month for swimming (with the highest average sea temperature) is August (68.3°F).
The coldest months (with the lowest average sea temperature) are January and February (58.9°F).

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Average daylight in September /
Average sunshine in September
San Clemente, CA

Average daylight in September / Average sunshine in September - San Clemente, CA
  • Average daylight in September: 12.4h

The month with the longest days is June (Average daylight: 14.3h).
The month with the shortest days is December (Average daylight: 10h).

  • Average sunshine in September: 10.2h

Months with the most sunshine are July and August (Average sunshine: 11.8h).
The month with the least sunshine is December (Average sunshine: 6.5h).

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Average sunshine days in September
San Clemente, CA

Average sunshine days in September - San Clemente, CA
  • Average sunshine days in September: 23.8 days

The month with the most sunshine days is October (26 days).
The month with the least sunshine days is February (21.6 days).

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Average UV index in September
San Clemente, CA

Average UV index in September - San Clemente, CA
  • Average UV index in September: 6

Months with the highest UV index are 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
San Clemente, CA

Average cloud cover in September - San Clemente, CA
  • Average cloud cover in September: 15

Months with the most cloud cover are March and May (Cloud cover 27).
The month with the least cloud cover is August (Cloud cover 11).

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Average visibility in September
San Clemente, CA

Average visibility in September - San Clemente, 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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