December weather forecast
San Diego, CA

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

Weather in December

December ushers in the winter season in San Diego, though winters here are relatively mild compared to most other parts of the United States. There is a noticeable increase in conditioned precipitation, with rainfall levels peeking at 1.65" (42mm). The cooler temperatures and increased rain make it a quieter month for visiting the beaches. Despite the shorter days and less sunshine, San Diego's winter still offers a fair share of sunny days. The mildly cold and occasionally wet weather can’t put a damper on the holiday spirit that spreads across the city.

Temperature

The arrival of December brings an average high-temperature of an enjoyable 63.3°F (17.4°C), subtly diverging from November's 68.5°F (20.3°C). During December, San Diego observes a consistent average nighttime temperature of 52.7°F (11.5°C).

Humidity

In December, the average relative humidity in San Diego, California, is 62%.

Rainfall

The month with the most rainfall is December, when the rain falls for 5.8 days and typically aggregates up to 1.65" (42mm) of precipitation.

Ocean temperature

In San Diego, the average seawater temperature in December is 60.4°F (15.8°C).
Note: Swimming in water that is 60.4°F (15.8°C) is not enjoyable for most. Breathing becomes more challenging to manage as the water temperature dips from 69.8°F (21°C) to 59°F (15°C).

Daylight

December has the shortest days of the year in San Diego, with an average of 10h and 0min of daylight.
On the first day of December in San Diego, sunrise is at 6:33 am and sunset at 4:42 pm. On the last day of the month, sunrise is at 6:50 am and sunset at 4:53 pm PST.

Sunshine

December has the least sunshine of the year in San Diego, with an average of 6.7h of sunshine.

UV index

January through March, November and December, with an average maximum UV index of 4, are months with the lowest UV index in San Diego. A UV Index value of 3 to 5 symbolizes a moderate health risk from exposure to the Sun's UV radiation for ordinary individuals.
Note: The maximum daily UV index, 4 in December, converts into the following recommendations:
Exercise prudence. Persons with fair skin could be burned in under 30 minutes. It's crucial to reduce time in the direct Sun around mid-day due to the intense solar radiation. In the presence of strong sunlight, it's crucial to wear sunglasses that ward off UVA and UVB rays.
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Frequently asked questions

What is the temperature in December in San Diego?

In San Diego, in December, the average high-temperature is 63.3°F (17.4°C), and the average low-temperature is 52.7°F (11.5°C).

What is the average humidity in December in San Diego?

In San Diego, the average relative humidity in December is 62%.

What is the wettest month in San Diego?

December is the month with the most rainfall in San Diego. Rain falls for 5.8 days and accumulates 1.65" (42mm) of precipitation.

How many days does it rain in December in San Diego?

In San Diego, California, in December, during 5.8 rainfall days, 1.65" (42mm) of precipitation is typically accumulated.

What is the ocean temperature in December in San Diego?

In San Diego, in December, the average water temperature is 60.4°F (15.8°C). Swimming in 60.4°F (15.8°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 month with the shortest days in San Diego?

December has the shortest days of the year, with an average of 10h and 0min of daylight.

How many hours of daylight does San Diego have in December?

In December, the average day length in San Diego is 10h and 2min.

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

In December, on the first day of the month, sunrise is at 6:33 am and sunset at 4:42 pm. On the last day of the month, sunrise is at 6:50 am and sunset at 4:53 pm PST.

What is the month with the least sunshine in San Diego?

With an average of 6.7h of sunshine, December has the least sunshine of the year in San Diego.

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

In San Diego, California, the average sunshine duration in December is 6.7h.

What are the months with the lowest UV index in San Diego?

January through March, November and December, with an average maximum UV index of 4, are months with the lowest UV index in San Diego, California.

How high is the UV index in December in San Diego?

In San Diego, California, the average daily maximum UV index in December is 4. A UV Index reading of 3 to 5 represents a moderate health threat from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
San Diego, CA

Average temperature in December - San Diego, CA
  • Average high temperature in December: 63.3°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 December: 52.7°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 December
San Diego, CA

Average pressure in December - San Diego, CA
  • Average pressure in December: 30.06"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 December
San Diego, CA

Average wind speed in December - San Diego, CA
  • Average wind speed in December: 5.5mph

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 December
San Diego, CA

Average humidity in December - San Diego, CA
  • Average humidity in December: 62%

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 December
San Diego, CA

Average rainfall in December - San Diego, CA
  • Average rainfall in December: 1.65"

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 December
San Diego, CA

Average rainfall days in December - San Diego, CA
  • Average rainfall days in December: 5.8 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 December
San Diego, CA

Average sea temperature in December - San Diego, CA
  • Average sea temperature in December: 60.4°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 December /
Average sunshine in December
San Diego, CA

Average daylight in December / Average sunshine in December - San Diego, CA
  • Average daylight in December: 10h and 0min

The month with the longest days is June (Average daylight: 14h and 18min).
The month with the shortest days is December (Average daylight: 10h and 0min).

  • Average sunshine in December: 6h and 4min

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 December
San Diego, CA

Average sunshine days in December - San Diego, CA
  • Average sunshine days in December: 23.2 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 December
San Diego, CA

Average UV index in December - San Diego, CA
  • Average UV index in December: 4

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 December
San Diego, CA

Average cloud cover in December - San Diego, CA
  • Average cloud cover in December: 24

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 December
San Diego, CA

Average visibility in December - San Diego, CA
  • Average visibility in December: 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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San Diego, California, USA

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