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December Weather in Santa Rosa, United States

Last updated: June 24, 2025

In December, the average temperature in Santa Rosa, United States hovers around 13°C (56°F). During this time, temperatures can dip as low as -1°C (31°F) or rise to a balmy 28°C (82°F). Expect about 18 mm (0.7 in) of precipitation spread over 3 days, accompanied by an average humidity of 82%, creating a distinctly moist atmosphere.

December Temperature in Santa Rosa

In December in Santa Rosa, the average temperature is 13°C (56°F). Maximum temperatures can reach 28°C (82°F), while the minimum can drop as low as -1°C (31°F). Be prepared for a wide range of temperatures when traveling during this time.

December Weather in Santa Rosa: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in Santa Rosa, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Santa Rosa, December typically has an average temperature of 13°C (56°F), with highs reaching up to 28°C (82°F) and lows dropping to around -1°C (31°F).
JanFebMarAprMayJunJulAugSepOctNovDec555764737989919186756655
Data source: Temperature data for Santa Rosa 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 Santa Rosa

In Santa Rosa in December, the precipitation amount is 18 mm (0.7 in) over a span of 3 days.

December Precipitation Trends in Santa Rosa

The chart displays monthly precipitation patterns in Santa Rosa, 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 Santa Rosa, December typically receives around 18 mm (0.7 inches) of precipitation spread over approximately 3 days.
JanFebMarAprMayJunJulAugSepOctNovDec1818132173424157818
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Santa Rosa

In Santa Rosa in December, humidity is 82%. With an average temperature of 13°C (56°F), this humidity feels like a damp blanket wrapping around you, making it feel much cooler than it is and creating a heavy atmosphere that can be exhausting for travelers.

December Average Humidity in Santa Rosa

This chart illustrates the average monthly humidity levels in Santa Rosa, 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 Santa Rosa is approximately 82%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%79%67%55%40%33%34%48%64%67%77%82%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Santa Rosa

In Santa Rosa 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 Santa Rosa for better planning.

Maximum UV Index Levels in Santa Rosa for December

The chart shows the monthly maximum UV Index (UVI) for Santa Rosa 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 Santa Rosa typically reaches 4, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec579111212121110864
Data source: Santa Rosa 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 Santa Rosa Compares to Other Months

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

This table compares monthly weather conditions in Santa Rosa, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather13°C (55°F)18 mm (0.7 inches)76%moderate
February Weather14°C (58°F)18 mm (0.7 inches)79%high
March Weather18°C (64°F)13 mm (0.5 inches)67%very high
April Weather23°C (73°F)2 mm (0.1 inches)55%extreme
May Weather26°C (79°F)1 mm (0.0 inches)40%extreme
June Weather32°C (89°F)7 mm (0.3 inches)33%extreme
July Weather33°C (91°F)34 mm (1.3 inches)34%extreme
August Weather33°C (91°F)24 mm (0.9 inches)48%extreme
September Weather30°C (86°F)15 mm (0.6 inches)64%very high
October Weather24°C (76°F)7 mm (0.3 inches)67%very high
November Weather19°C (66°F)8 mm (0.3 inches)77%high
December Weather13°C (56°F)18 mm (0.7 inches)82%moderate

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