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December Weather in San Jose, United States

Last updated: June 24, 2025

In San Jose, United States, the average temperature in December is a crisp 9°C (48°F). Expect a range from a chilly -4°C (25°F) to a pleasant 23°C (74°F). During this month, precipitation measures approximately 25 mm (1.0 in) over 4 days, and humidity hovers around an average of 84%. Prepare accordingly for a mix of weather!

December Temperature in San Jose

In December in San Jose, the average temperature is 9°C (48°F). Maximums can reach 23°C (74°F), while minimums can dip as low as -4°C (25°F). This unpredictable weather makes San Jose an ideal destination for travelers looking to experience both mild and chilly conditions.

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

The chart illustrates December temperature patterns in San Jose, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In San Jose, December typically has an average temperature of 9°C (48°F), with highs reaching up to 23°C (74°F) and lows dropping to around -4°C (25°F).
JanFebMarAprMayJunJulAugSepOctNovDec465058687686868579685848
Data source: Temperature data for San Jose 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 Jose

In San Jose in December, the precipitation amount is 25 mm (1.0 in) over the course of 4 days.

December Precipitation Trends in San Jose

The chart displays monthly precipitation patterns in San Jose, 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 Jose, December typically receives around 25 mm (1.0 inches) of precipitation spread over approximately 4 days.
JanFebMarAprMayJunJulAugSepOctNovDec233216234452228132025
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in San Jose

In San Jose in December, humidity is 84%. With an average temperature of 9°C (48°F), this humidity feels like a damp chill that envelops you, making it essential to dress in layers and stay active, as the moisture in the air can quickly lead to discomfort while traveling.

December Average Humidity in San Jose

This chart illustrates the average monthly humidity levels in San Jose, 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 Jose is approximately 84%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec81%82%68%55%45%37%43%53%66%72%81%84%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in San Jose

In San Jose 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 Jose for better planning.

Maximum UV Index Levels in San Jose for December

The chart shows the monthly maximum UV Index (UVI) for San Jose 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 Jose typically reaches 4, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec5710111212121211864
Data source: San Jose 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 Jose Compares to Other Months

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

This table compares monthly weather conditions in San Jose, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather8°C (47°F)23 mm (0.9 inches)81%moderate
February Weather10°C (50°F)32 mm (1.2 inches)82%high
March Weather15°C (59°F)16 mm (0.6 inches)68%very high
April Weather20°C (68°F)2 mm (0.1 inches)55%extreme
May Weather24°C (76°F)3 mm (0.1 inches)45%extreme
June Weather30°C (86°F)4 mm (0.2 inches)37%extreme
July Weather30°C (86°F)45 mm (1.8 inches)43%extreme
August Weather29°C (85°F)22 mm (0.9 inches)53%extreme
September Weather26°C (79°F)28 mm (1.1 inches)66%extreme
October Weather20°C (68°F)13 mm (0.5 inches)72%very high
November Weather14°C (58°F)20 mm (0.8 inches)81%high
December Weather9°C (48°F)25 mm (1.0 inches)84%moderate

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