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December Weather in Sun Valley, United States

Last updated: June 24, 2025

In December, the average temperature in Sun Valley, United States hovers around 0°C (32°F). However, be prepared for a range of conditions: the minimum can dip to a chilly -15°C (5°F), while the maximum can reach a mild 14°C (58°F). Expect some moisture, with 64 mm (2.5 in) of precipitation spread over 8 days and an average humidity level of 82%, creating a brisk yet refreshing atmosphere.

December Temperature in Sun Valley

In December in Sun Valley, the average temperature is 0°C (32°F), with maximums reaching 14°C (58°F) and minimums dropping as low as -15°C (5°F). Travelers should prepare for chilly weather and layers to enjoy their visit comfortably.

December Weather in Sun Valley: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in Sun Valley, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Sun Valley, December typically has an average temperature of 0°C (32°F), with highs reaching up to 14°C (58°F) and lows dropping to around -15°C (5°F).
JanFebMarAprMayJunJulAugSepOctNovDec323338475566747364504132
Data source: Temperature data for Sun Valley 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 Sun Valley

In Sun Valley in December, the precipitation amount is 64 mm (2.5 in) over the course of 8 days.

December Precipitation Trends in Sun Valley

The chart displays monthly precipitation patterns in Sun Valley, 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 Sun Valley, December typically receives around 64 mm (2.5 inches) of precipitation spread over approximately 8 days.
JanFebMarAprMayJunJulAugSepOctNovDec9187713239811118333965
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Sun Valley

In Sun Valley in December, humidity is 82%. With an average temperature of 0°C (32°F), this humidity feels like an icy breath enveloping you, making each step outdoors a challenge as the cold dampness seeps into your clothes, chilling you to the bone and sapping your energy while traveling.

December Average Humidity in Sun Valley

This chart illustrates the average monthly humidity levels in Sun Valley, 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 Sun Valley is approximately 82%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec85%87%84%78%64%56%44%34%41%60%81%82%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Sun Valley

In Sun Valley 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 Sun Valley, you can check the information here.

Maximum UV Index Levels in Sun Valley for December

The chart shows the monthly maximum UV Index (UVI) for Sun Valley 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 Sun Valley typically reaches 3, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec46891112121110743
Data source: Sun Valley 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 Sun Valley Compares to Other Months

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

This table compares monthly weather conditions in Sun Valley, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather0°C (33°F)91 mm (3.6 inches)85%moderate
February Weather1°C (34°F)87 mm (3.4 inches)87%high
March Weather3°C (38°F)71 mm (2.8 inches)84%very high
April Weather8°C (47°F)32 mm (1.3 inches)78%very high
May Weather13°C (55°F)39 mm (1.5 inches)64%extreme
June Weather19°C (67°F)8 mm (0.3 inches)56%extreme
July Weather24°C (75°F)11 mm (0.4 inches)44%extreme
August Weather23°C (73°F)11 mm (0.4 inches)34%extreme
September Weather18°C (64°F)8 mm (0.3 inches)41%very high
October Weather10°C (51°F)33 mm (1.3 inches)60%high
November Weather5°C (42°F)39 mm (1.5 inches)81%moderate
December Weather0°C (32°F)64 mm (2.5 inches)82%moderate

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