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December Weather in San Dimas, United States

Last updated: June 24, 2025

In San Dimas, United States, the average temperature in December hovers around 12°C (54°F). Expect a minimum of 2°C (36°F) and a comfortable maximum of 27°C (81°F). During this month, you can anticipate about 79 mm (3.1 in) of precipitation spread across 5 days, with an average humidity level of 71%.

December Temperature in San Dimas

In December in San Dimas, the average temperature is 12°C (54°F). Maximum temperatures can reach 27°C (81°F) while minimums can drop as low as 2°C (36°F). Be sure to pack layers to enjoy the pleasant days and stay warm during the cooler nights!

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

The chart illustrates December temperature patterns in San Dimas, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In San Dimas, December typically has an average temperature of 12°C (54°F), with highs reaching up to 27°C (81°F) and lows dropping to around 2°C (36°F).
JanFebMarAprMayJunJulAugSepOctNovDec545456626470767674686154
Data source: Temperature data for San Dimas 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 Dimas

In San Dimas in December, the precipitation amount is 79 mm (3.1 in) over a span of 5 days.

December Precipitation Trends in San Dimas

The chart displays monthly precipitation patterns in San Dimas, 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 Dimas, December typically receives around 79 mm (3.1 inches) of precipitation spread over approximately 5 days.
JanFebMarAprMayJunJulAugSepOctNovDec80707627171123122679
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in San Dimas

In San Dimas in December humidity is 71%. With an average temperature of 12°C (54°F), this humidity feels like a damp chill that clings to your skin, making it essential to dress in layers while exploring the area, as the cool air can be refreshing yet slightly uncomfortable without proper attire for outdoor activities.

December Average Humidity in San Dimas

This chart illustrates the average monthly humidity levels in San Dimas, 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 Dimas is approximately 71%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec74%79%75%71%70%72%73%69%68%67%68%71%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in San Dimas

In San Dimas in December, the maximum UV index reaches 4, which corresponds to a moderate Exposure Category. With a time to burn of 30 minutes, it’s important to take precautions to protect your skin. You can find more details in the Hourly UV Index in San Dimas for better planning.

Maximum UV Index Levels in San Dimas for December

The chart shows the monthly maximum UV Index (UVI) for San Dimas 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 Dimas typically reaches 4, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec468101012111010754
Data source: San Dimas 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 Dimas Compares to Other Months

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

This table compares monthly weather conditions in San Dimas, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather12°C (54°F)80 mm (3.1 inches)74%moderate
February Weather12°C (55°F)70 mm (2.8 inches)79%high
March Weather14°C (57°F)76 mm (3.0 inches)75%very high
April Weather16°C (62°F)27 mm (1.1 inches)70%very high
May Weather18°C (64°F)17 mm (0.7 inches)70%very high
June Weather21°C (70°F)1 mm (0.0 inches)72%extreme
July Weather24°C (76°F)1 mm (0.1 inches)73%extreme
August Weather25°C (77°F)2 mm (0.1 inches)69%very high
September Weather23°C (74°F)3 mm (0.1 inches)68%very high
October Weather20°C (68°F)12 mm (0.5 inches)67%high
November Weather16°C (61°F)26 mm (1.0 inches)68%moderate
December Weather12°C (54°F)79 mm (3.1 inches)71%moderate

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