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December Weather in Walnut Creek, United States

Last updated: June 24, 2025

In December, the average temperature in Walnut Creek, United States hovers around 2°C (36°F), with minima dipping as low as -16°C (4°F) and maxima reaching up to 18°C (65°F). Expect 95 mm (3.8 in) of precipitation spread over 11 days, accompanied by a notable average humidity of 86%.

December Temperature in Walnut Creek

In December in Walnut Creek, the average temperature is 2°C (36°F), with maximums reaching 18°C (65°F) and minimums dipping as low as -16°C (4°F). Travelers should be prepared for a wide range of temperatures, making versatile clothing essential for enjoying the varied weather.

December Weather in Walnut Creek: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in Walnut Creek, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Walnut Creek, December typically has an average temperature of 2°C (36°F), with highs reaching up to 18°C (65°F) and lows dropping to around -16°C (4°F).
JanFebMarAprMayJunJulAugSepOctNovDec303441516371757368574236
Data source: Temperature data for Walnut Creek 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 Walnut Creek

In Walnut Creek in December, the precipitation amount is 95 mm (3.8 in) spread over 11 days.

December Precipitation Trends in Walnut Creek

The chart displays monthly precipitation patterns in Walnut Creek, 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 Walnut Creek, December typically receives around 95 mm (3.8 inches) of precipitation spread over approximately 11 days.
JanFebMarAprMayJunJulAugSepOctNovDec89106103129123126119861051099495
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Walnut Creek

In Walnut Creek in December, humidity is 86%. With an average temperature of 2°C (36°F), this humidity feels like a biting chill that clings to your skin, making outdoor exploration uncomfortable and dampening any enthusiasm for travel.

December Average Humidity in Walnut Creek

This chart illustrates the average monthly humidity levels in Walnut Creek, 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 Walnut Creek is approximately 86%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec89%88%87%87%81%83%82%76%77%82%89%86%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Walnut Creek

In Walnut Creek in December, the maximum UV index is 2, which corresponds to a low exposure category. With this level of UV radiation, the time to burn is approximately 45 minutes. To learn more about the hourly UV index in Walnut Creek, you can visit Hourly UV Index in Walnut Creek.

Maximum UV Index Levels in Walnut Creek for December

The chart shows the monthly maximum UV Index (UVI) for Walnut Creek 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 Walnut Creek typically reaches 2, which falls under the low exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356910101098642
Data source: Walnut Creek 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 Walnut Creek Compares to Other Months

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

This table compares monthly weather conditions in Walnut Creek, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-1°C (31°F)88 mm (3.5 inches)88%moderate
February Weather1°C (34°F)106 mm (4.2 inches)88%moderate
March Weather5°C (42°F)103 mm (4.1 inches)87%high
April Weather11°C (51°F)129 mm (5.1 inches)87%very high
May Weather17°C (63°F)122 mm (4.8 inches)81%very high
June Weather22°C (71°F)126 mm (5.0 inches)83%very high
July Weather24°C (76°F)118 mm (4.7 inches)82%very high
August Weather23°C (73°F)86 mm (3.4 inches)76%very high
September Weather20°C (68°F)105 mm (4.2 inches)77%very high
October Weather14°C (57°F)109 mm (4.3 inches)82%high
November Weather5°C (42°F)94 mm (3.7 inches)89%moderate
December Weather2°C (36°F)95 mm (3.8 inches)86%low

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