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December Weather in San Diego, United States

Last updated: June 24, 2025

In December, the average temperature in San Diego, United States hovers around 16°C (61°F), with extremes ranging from a chilly 0°C (32°F) to a warm 34°C (93°F). During this month, expect about 38 mm (1.5 in) of precipitation spread over 4 days, contributing to the region's average humidity of 86%.

December Temperature in San Diego

In December in San Diego, the average temperature is 16°C (61°F). Maximums can reach 34°C (93°F), while minimums can drop to as low as 0°C (32°F). This diverse temperature range makes San Diego a great destination for travelers seeking both warm and cool experiences during their visit.

December Weather in San Diego: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in San Diego, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In San Diego, December typically has an average temperature of 16°C (61°F), with highs reaching up to 34°C (93°F) and lows dropping to around 0°C (32°F).
JanFebMarAprMayJunJulAugSepOctNovDec586169748184858682756661
Data source: Temperature data for San Diego generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

December Precipitation in San Diego

In San Diego in December, the total precipitation amount is 38 mm (1.5 in) spread over the course of 4 days.

December Precipitation Trends in San Diego

The chart displays monthly precipitation patterns in San Diego, with values for each month alongside December’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how December’s conditions compare to those of other months. In San Diego, December typically receives around 38 mm (1.5 inches) of precipitation spread over approximately 4 days.
JanFebMarAprMayJunJulAugSepOctNovDec2724544199887952104443738
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in San Diego

In San Diego in December, humidity is 86%. With an average temperature of 16°C (61°F), this humidity feels like walking through a warm, thick blanket of air that clings to your skin, making outdoor activities feel sticky and uncomfortable for traveling.

December Average Humidity in San Diego

This chart illustrates the average monthly humidity levels in San Diego, with December’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In December, average humidity in San Diego is approximately 86%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec83%79%76%77%80%73%66%65%73%76%80%86%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in San Diego

In San Diego in December, the maximum UV index reaches 5, which corresponds to a moderate Exposure Category. Under these conditions, the estimated time to burn is approximately 30 minutes. For more details, you can check the Hourly UV Index in San Diego.

Maximum UV Index Levels in San Diego for December

The chart shows the monthly maximum UV Index (UVI) for San Diego in December, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In December, the maximum UV index in San Diego typically reaches 5, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec6810111112121211975
Data source: San Diego December UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How December Weather in San Diego Compares to Other Months

Weather in San Diego varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in San Diego, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in San Diego, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather14°C (58°F)27 mm (1.1 inches)83%high
February Weather16°C (61°F)24 mm (1.0 inches)79%very high
March Weather21°C (69°F)54 mm (2.1 inches)76%very high
April Weather24°C (75°F)41 mm (1.6 inches)77%extreme
May Weather27°C (81°F)99 mm (3.9 inches)80%extreme
June Weather29°C (84°F)88 mm (3.4 inches)73%extreme
July Weather30°C (86°F)79 mm (3.1 inches)66%extreme
August Weather30°C (87°F)52 mm (2.1 inches)65%extreme
September Weather28°C (82°F)104 mm (4.1 inches)73%extreme
October Weather24°C (76°F)44 mm (1.7 inches)76%very high
November Weather19°C (66°F)37 mm (1.4 inches)80%high
December Weather16°C (61°F)38 mm (1.5 inches)86%moderate

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