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December Weather in Walnut Creek, United States

Last updated: June 24, 2025

In Walnut Creek, United States, the average temperature in December hovers around 10°C (50°F). Be prepared for a range, as temperatures can dip to a chilly 2°C (36°F) or soar to a warm 24°C (75°F). Expect 75 mm (2.9 in) of precipitation spread over 8 days, accompanied by an average humidity of 80%.

December Temperature in Walnut Creek

In December in Walnut Creek, the average temperature is 10°C (50°F), with maximums reaching up to 24°C (75°F) and minimums dropping as low as 2°C (36°F). This variation in temperature offers travelers a mix of mild days and cooler evenings, making it a great time to explore the area while dressing in layers.

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 10°C (50°F), with highs reaching up to 24°C (75°F) and lows dropping to around 2°C (36°F).
JanFebMarAprMayJunJulAugSepOctNovDec505255596368686968645650
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 75 mm (2.9 in) over a span of 8 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 75 mm (2.9 inches) of precipitation spread over approximately 8 days.
JanFebMarAprMayJunJulAugSepOctNovDec99897231161001233775
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 80%. With an average temperature of 10°C (50°F), this humidity feels like a damp chill enveloping you, making traveling somewhat uncomfortable as it seeps into your clothes and clings to your skin, leaving you longing for a cozy indoor refuge.

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 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%84%82%78%71%64%59%54%55%62%78%80%
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 3, which corresponds to a moderate Exposure Category. The time to burn is approximately 30 minutes. For more details on the hourly UV index in Walnut Creek, you can check the information here.

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 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3589101111109643
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 Weather10°C (50°F)99 mm (3.9 inches)82%moderate
February Weather11°C (53°F)89 mm (3.5 inches)84%moderate
March Weather13°C (55°F)72 mm (2.8 inches)82%very high
April Weather15°C (59°F)31 mm (1.2 inches)78%very high
May Weather17°C (63°F)16 mm (0.6 inches)71%very high
June Weather20°C (68°F)1 mm (0.1 inches)64%extreme
July Weather20°C (68°F)0 mm (0.0 inches)58%extreme
August Weather20°C (69°F)0 mm (0.0 inches)54%very high
September Weather20°C (69°F)1 mm (0.0 inches)55%very high
October Weather18°C (64°F)23 mm (0.9 inches)62%high
November Weather13°C (56°F)37 mm (1.5 inches)78%moderate
December Weather10°C (50°F)75 mm (2.9 inches)80%moderate

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