December weather forecast and climate
San Diego, CA

The view of Coronado Island in San Diego, California, from across a water body on a sidewalk, with a row of palm trees
The view of Coronado Island in San Diego, California, from across a water body on a sidewalk, with a row of palm trees
December is the coldest month of the year as the winter descends in San Diego. The lower latitude location and the proximity to the ocean ensure that the cold is mild at best, and rarely touches freezing temperatures. The average temperature lies in the 48°F (8.9°C) to 65°F (18.3°C) range, with most days in December touching at least 60°F (15.6°C).
The 10-hour days with daily 7.5-hour sunshine are the shortest of the year and register 1.5" (38.1mm) of rainfall. San Diego rarely has a white Christmas, and most of the visitors who come from the frigid north prefer its warm winter weather to the severe cold back home.

What is the coldest month in San Diego?

The coldest month in San Diego, California, is December, with an average high-temperature of 64.8°F (18.2°C) and an average low-temperature of 48.4°F (9.1°C).

What is the temperature in December in San Diego?

The average high-temperature, in December, in San Diego, California, is 64.8°F (18.2°C), while the average low-temperature is 48.4°F (9.1°C).

What is the average humidity in December in San Diego?

In December, the average relative humidity in San Diego is 63.7%.

How much does it rain in San Diego in December?

In December, in San Diego, California, the rain falls for 5.8 days. Throughout December, 1.5" (37mm) of precipitation is accumulated.

What is the ocean temperature in December in San Diego?

In San Diego, California, in December, the average water temperature is 60.4°F (15.8°C). For swimming, a surface water temperature of 60.4°F (15.8°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).

What is the month with the shortest days in San Diego?

The month with the shortest days is December, with an average of 10h of daylight.

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

In December, the average length of the day in San Diego is 10h.

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

With an average of 7.5h of sunshine, December has the least sunshine of the year in San Diego, California.

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

The average sunshine in December in San Diego is 7.5h.

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

Months with the lowest UV index in San Diego are January and December, with an average UV index of 3.

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

In San Diego, California, the average UV index in December is 3.
Average temperature in December - San Diego, CA
  • Average high temperature in December: 64.7°F

The warmest month (with the highest average high temperature) is August (76.4°F).
The month with the lowest average high temperature is December (64.7°F).

  • Average low temperature in December: 48.4°F

The month with the highest average low temperature is August (66.7°F).
The coldest month (with the lowest average low temperature) is December (48.4°F).

Average humidity in December - San Diego, CA
  • Average humidity in December: 63.7%

The month with the highest relative humidity is July (74.6%).
The month with the lowest relative humidity is January (63.1%).

Average rainfall in December - San Diego, CA
  • Average rainfall in December: 1.5"

The wettest month (with the highest rainfall) is January (2.1").
The driest month (with the lowest rainfall) is July (0").

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 February (7.1 days).
The month with the lowest number of rainy days is August (0.4 days).

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).

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

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

  • Average sunshine in December: 7.5h

The month with most sunshine is July (Average sunshine: 9.8h).
The month with least sunshine is December (Average sunshine: 7.5h).

Average UV index in December - San Diego, CA
  • Average UV index in December: 3

Months with the highest UV index are June, July and August (UV index 10).
Months with the lowest UV index are January and December (UV index 3).

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