nomadseason

December Weather in Boise, United States

Last updated: June 24, 2025

In December, the average temperature in Boise, United States hovers around 1°C (34°F). Be prepared for chilly extremes, as temperatures can drop to a brisk -11°C (13°F), while occasionally reaching a mild 14°C (58°F). Expect 40 mm (1.6 in) of precipitation spread over 10 days, contributing to a notably high average humidity of 87%.

December Temperature in Boise

In December in Boise, the average temperature is 1°C (34°F), with maximums reaching 14°C (58°F) and minimums dropping as low as -11°C (13°F). Travelers should be prepared for significant temperature fluctuations and pack accordingly for both chilly days and milder conditions.

December Weather in Boise: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in Boise, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Boise, December typically has an average temperature of 1°C (34°F), with highs reaching up to 14°C (58°F) and lows dropping to around -11°C (13°F).
JanFebMarAprMayJunJulAugSepOctNovDec333646526070817867524334
Data source: Temperature data for Boise generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
The average of daily temperatures (24 hours) calculated across all days in the month.

December Precipitation in Boise

In Boise in December, the precipitation amount is 40 mm (1.6 in) over a span of 10 days.

December Precipitation Trends in Boise

The chart displays monthly precipitation patterns in Boise, 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 Boise, December typically receives around 40 mm (1.6 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec4951383639211810223240
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

December Humidity in Boise

In Boise in December humidity is 87%. With an average temperature of 1°C (34°F), this humidity feels like a chilling blanket enveloping you, making every step outside feel heavy and damp, and leaving you longing for warmth and comfort while traveling.

December Average Humidity in Boise

This chart illustrates the average monthly humidity levels in Boise, 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 Boise is approximately 87%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%89%85%79%71%71%66%50%48%65%84%87%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Boise

In Boise 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 Boise, you can visit Hourly UV Index in Boise.

Maximum UV Index Levels in Boise for December

The chart shows the monthly maximum UV Index (UVI) for Boise 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 Boise typically reaches 2, which falls under the low exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec356810111198642
Data source: Boise 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 Boise Compares to Other Months

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

This table compares monthly weather conditions in Boise, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather1°C (33°F)49 mm (1.9 inches)88%moderate
February Weather2°C (36°F)50 mm (2.0 inches)89%moderate
March Weather8°C (46°F)38 mm (1.5 inches)85%high
April Weather11°C (52°F)36 mm (1.4 inches)79%very high
May Weather16°C (61°F)39 mm (1.5 inches)71%very high
June Weather21°C (71°F)21 mm (0.8 inches)71%extreme
July Weather27°C (81°F)1 mm (0.0 inches)66%extreme
August Weather26°C (78°F)8 mm (0.3 inches)50%very high
September Weather20°C (68°F)10 mm (0.4 inches)48%very high
October Weather11°C (53°F)22 mm (0.9 inches)65%high
November Weather6°C (43°F)32 mm (1.3 inches)84%moderate
December Weather1°C (34°F)40 mm (1.6 inches)87%low

Compare Boise's Climate with Cities Worldwide