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 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?

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

How much does it rain in San Diego in December?

In San Diego, in December, it is raining for 5.8 days, with typically 1.5" (37mm) of accumulated precipitation.
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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