San Diego
California, USA
Long-term weather forecast
Long-term weather forecast
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December weather forecast and Climate
San Diego, CA

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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 around 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.
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  • The 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).

  • The 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).

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  • The 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%).

  • The 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").

  • The 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).

  • The 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).

  • The average daylight in December: 10h

Months with the longest days are May, June and July (Average daylight: 14h).
Months with shortest days are January, November and December (Average daylight: 10h).

  • The 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).

  • The 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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