Last updated: June 24, 2025
In December, the average temperature in Boise City, United States hovers around 4°C (39°F). Expect a wide range, with minimums plummeting to -17°C (2°F) and maximums reaching 24°C (75°F). Additionally, you can anticipate roughly 15 mm (0.6 in) of precipitation over the course of a single day, while the average humidity lingers at a comfortable 78%.
In December in Boise City, the average temperature is 4°C (39°F), with maximums reaching 24°C (75°F) and minimums dropping to as low as -17°C (2°F). Travelers should be prepared for a wide range of temperatures, making layered clothing a smart choice.
In Boise City in December, the precipitation amount is 15 mm (0.6 in) over the course of 1 day.
In Boise City in December humidity is 78%. With an average temperature of 4°C (39°F), this humidity feels like a damp chill that seeps into your bones, making outdoor exploration somewhat uncomfortable and necessitating the need for warm, weatherproof clothing to fully enjoy your travels.
In Boise City 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 Boise City, you can check the information here.
UV Risk Categories
Weather in Boise City varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Boise City, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 2°C (36°F) | 16 mm (0.6 inches) | 73% | moderate |
| February Weather | 3°C (37°F) | 11 mm (0.4 inches) | 76% | high |
| March Weather | 9°C (49°F) | 36 mm (1.4 inches) | 64% | very high |
| April Weather | 13°C (55°F) | 41 mm (1.6 inches) | 61% | very high |
| May Weather | 18°C (64°F) | 60 mm (2.4 inches) | 71% | extreme |
| June Weather | 24°C (76°F) | 37 mm (1.5 inches) | 75% | extreme |
| July Weather | 26°C (79°F) | 44 mm (1.7 inches) | 75% | extreme |
| August Weather | 25°C (77°F) | 55 mm (2.2 inches) | 80% | extreme |
| September Weather | 22°C (71°F) | 32 mm (1.3 inches) | 80% | very high |
| October Weather | 13°C (56°F) | 34 mm (1.3 inches) | 78% | high |
| November Weather | 8°C (47°F) | 7 mm (0.3 inches) | 76% | moderate |
| December Weather | 4°C (39°F) | 15 mm (0.6 inches) | 78% | moderate |