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December Weather in San Bernardino, United States

Last updated: June 24, 2025

In December, the average temperature in San Bernardino, United States hovers around 11°C (51°F), making it a cool yet pleasant time of the year. Expect a minimum chill of -1°C (30°F) and a warm peak of 27°C (80°F). During this month, you can anticipate 70 mm (2.7 in) of precipitation, spread over about 5 days, with a 74% average humidity adding to the overall atmosphere. 🌦️

December Temperature in San Bernardino

In December in San Bernardino, the average temperature is 11°C (51°F). Maximums can reach 27°C (80°F) and minimums can be as low as -1°C (30°F). Be prepared for a range of temperatures and pack accordingly for your trip!

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

The chart illustrates December temperature patterns in San Bernardino, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In San Bernardino, December typically has an average temperature of 11°C (51°F), with highs reaching up to 27°C (80°F) and lows dropping to around -1°C (30°F).
JanFebMarAprMayJunJulAugSepOctNovDec515154606472787874665951
Data source: Temperature data for San Bernardino 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 Bernardino

In San Bernardino in December, the total precipitation amount is 70 mm (2.7 in) over the course of 5 days.

December Precipitation Trends in San Bernardino

The chart displays monthly precipitation patterns in San Bernardino, 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 Bernardino, December typically receives around 70 mm (2.7 inches) of precipitation spread over approximately 5 days.
JanFebMarAprMayJunJulAugSepOctNovDec70707531183111010112870
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in San Bernardino

In San Bernardino in December, humidity is 74%. With an average temperature of 11°C (51°F), this humidity feels like a damp chill that seeps into your bones, making outdoor exploration a bit uncomfortable and encouraging visitors to seek refuge in cozy cafés or indoor attractions.

December Average Humidity in San Bernardino

This chart illustrates the average monthly humidity levels in San Bernardino, 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 Bernardino is approximately 74%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec72%77%67%56%46%48%46%42%52%58%66%74%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in San Bernardino

In San Bernardino 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 Bernardino for better planning.

Maximum UV Index Levels in San Bernardino for December

The chart shows the monthly maximum UV Index (UVI) for San Bernardino 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 Bernardino typically reaches 4, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec469101112121110854
Data source: San Bernardino 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 Bernardino Compares to Other Months

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

This table compares monthly weather conditions in San Bernardino, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather11°C (51°F)70 mm (2.8 inches)72%moderate
February Weather11°C (52°F)70 mm (2.7 inches)77%high
March Weather12°C (54°F)75 mm (2.9 inches)67%very high
April Weather16°C (61°F)31 mm (1.2 inches)56%very high
May Weather18°C (64°F)18 mm (0.7 inches)46%extreme
June Weather22°C (72°F)3 mm (0.1 inches)48%extreme
July Weather26°C (78°F)11 mm (0.4 inches)46%extreme
August Weather26°C (79°F)10 mm (0.4 inches)42%extreme
September Weather23°C (74°F)10 mm (0.4 inches)52%very high
October Weather19°C (66°F)11 mm (0.4 inches)58%very high
November Weather15°C (59°F)28 mm (1.1 inches)66%moderate
December Weather11°C (51°F)70 mm (2.7 inches)74%moderate

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