September weather forecast
San Diego, CA

Coronado Island in San Diego, California, USA,
Coronado Island in San Diego, California, USA,

Weather in September

September, the first month of the autumn in San Diego, is also a moderately hot month, with an average temperature fluctuating between 65.1°F (18.4°C) and 76.6°F (24.8°C).

Temperature

In San Diego, the average high-temperature in September is relatively the same as in August - a still warm 76.6°F (24.8°C). In San Diego, the average low-temperature is 65.1°F (18.4°C).

Humidity

In September, the average relative humidity is 68%.

Rainfall

In San Diego, California, during 4.5 rainfall days, 0.39" (10mm) of precipitation is typically accumulated. Throughout the year, in San Diego, there are 61.8 rainfall days, and 8.7" (221mm) of precipitation is accumulated.

Ocean temperature

In San Diego, the average water temperature is 66.7°F (19.3°C).
Note: For swimming, a surface water temperature of 66.7°F (19.3°C) is not enjoyable for the majority. It is not considered safe, as controlling breathing becomes progressively more difficult as water temperature decreases below 69.8°F (21°C).

Daylight

The average length of the day in September in San Diego is 12h and 22min.
On the first day of the month, sunrise is at 6:23 am and sunset at 7:13 pm. On the last day of September, in San Diego, sunrise is at 6:42 am and sunset at 6:34 pm PDT.

Sunshine

In September, the average sunshine is 10.3h.

UV index

July through September, with an average maximum UV index of 6, are months with the highest UV index. A UV Index value of 6 to 7 symbolizes a high health hazard from exposure to the Sun's UV radiation for ordinary individuals.
Note: The average daily UV index of 6 in September transform into the following instructions:
Take precautions and utilize sun safety practices. Protection against 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. 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 average humidity in September in San Diego?

The average relative humidity in September is 68%.

How much does it rain in San Diego in September?

In September, the rain falls for 4.5 days. Throughout September, 0.39" (10mm) of precipitation is accumulated.

What is the ocean temperature in September in San Diego?

In San Diego, the average seawater temperature in September is 66.7°F (19.3°C). Swimming in 66.7°F (19.3°C) is not enjoyable for the majority. Controlling breathing becomes progressively more difficult as surface water temperature decreases below 69.8°F (21°C).

What is the average length of the day in September in San Diego?

The average day length in September in San Diego is 12h and 22min.

What time are sunrise and sunset in September in San Diego?

On the first day of September in San Diego, California, sunrise is at 6:23 am and sunset at 7:13 pm. On the last day of the month, sunrise is at 6:42 am and sunset at 6:34 pm PDT.

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

In San Diego, California, the average sunshine duration in September is 10.3h.

When is the highest UV index in San Diego?

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

What is the UV index reading in September in San Diego?

The average daily maximum UV index in September in San Diego, California, is 6. A UV Index value of 6 to 7 symbolizes a high health threat from exposure to Sun's UV rays.

Average temperature in September
San Diego, CA

Average temperature in September - San Diego, CA
  • Average high temperature in September: 76.6°F

The warmest month (with the highest average high temperature) is August (77.4°F).
The month with the lowest average high temperature is February (63.1°F).

  • Average low temperature in September: 65.1°F

The month with the highest average low temperature is August (65.7°F).
The coldest month (with the lowest average low temperature) is February (51.8°F).

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Average pressure in September
San Diego, CA

Average pressure in September - San Diego, CA
  • Average pressure in September: 29.88"Hg

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

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Average wind speed in September
San Diego, CA

Average wind speed in September - San Diego, CA
  • Average wind speed in September: 5.4mph

The windiest months (with the highest average wind speed) are April and May (6.3mph).
The calmest month (with the lowest average wind speed) is October (5.2mph).

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Average humidity in September
San Diego, CA

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

The month with the highest relative humidity is June (73%).
The month with the lowest relative humidity is November (59%).

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Average rainfall in September
San Diego, CA

Average rainfall in September - San Diego, CA
  • Average rainfall in September: 0.39"

The wettest month (with the highest rainfall) is December (1.65").
The driest month (with the least rainfall) is June (0.12").

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Average rainfall days in September
San Diego, CA

Average rainfall days in September - San Diego, CA
  • Average rainfall days in September: 4.5 days

The month with the highest number of rainy days is March (7.6 days).
The month with the least rainy days is June (2.7 days).

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Average sea temperature in September
San Diego, CA

Average sea temperature in September - San Diego, CA
  • Average sea temperature in September: 66.7°F

The best month for swimming (with the highest average sea temperature) is August (67.9°F).
The coldest month (with the lowest average sea temperature) is February (58.7°F).

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

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

The month with the longest days is June (Average daylight: 14h and 16min).
The month with the shortest days is December (Average daylight: 10h and 2min).

  • Average sunshine in September: 10h and 18min

The months with the most sunshine are July and August (Average sunshine: 11h and 54min).
The month with the least sunshine is December (Average sunshine: 6h and 42min).

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Average sunshine days in September
San Diego, CA

Average sunshine days in September - San Diego, CA
  • Average sunshine days in September: 21.8 days

The month with the most sunshine days is January (24.3 days).
The month with the least sunshine days is July (20.3 days).

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Average UV index in September
San Diego, CA

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

The months with the highest UV index are 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
San Diego, CA

Average cloud cover in September - San Diego, CA
  • Average cloud cover in September: 12

The month with the most cloud cover is December (Cloud cover 24).
The month with the least cloud cover is August (Cloud cover 9).

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Average visibility in September
San Diego, CA

Average visibility in September - San Diego, 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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