Last updated: June 24, 2025
In December, the average temperature in Challis, United States hovers around -9°C (16°F), with minimums dipping as low as -30°C (-21°F) and maximums reaching up to 9°C (49°F). Expect 38 mm (1.5 in) of precipitation sprinkled over 11 days, contributing to a high average humidity of 96%. Prepare for a chilly and damp month, making it essential to bundle up and stay cozy!
In December in Challis, the average temperature is -9°C (16°F). The maximum can reach 9°C (49°F), while the minimum can drop to as low as -30°C (-21°F). Travelers should be prepared for extremely cold conditions and dress in layers to enjoy their visit comfortably.
In Challis in December, the total precipitation amount is 38 mm (1.5 in) over a span of 11 days.
In Challis in December, humidity is 96%. With an average temperature of -9°C (16°F), this humidity feels like a heavy, biting chill that clings to your skin, making travel outside feel like stepping into a frigid mist that numbs your senses and dampens your spirit.
In Challis 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 Challis, you can visit Hourly UV Index in Challis.
UV Risk Categories
Weather in Challis varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Challis, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -9°C (16°F) | 34 mm (1.3 inches) | 94% | moderate |
| February Weather | -8°C (18°F) | 65 mm (2.6 inches) | 93% | moderate |
| March Weather | -3°C (27°F) | 40 mm (1.6 inches) | 91% | very high |
| April Weather | 0°C (33°F) | 49 mm (1.9 inches) | 87% | very high |
| May Weather | 6°C (44°F) | 68 mm (2.7 inches) | 83% | extreme |
| June Weather | 13°C (55°F) | 59 mm (2.3 inches) | 80% | extreme |
| July Weather | 18°C (65°F) | 18 mm (0.7 inches) | 75% | extreme |
| August Weather | 17°C (63°F) | 23 mm (0.9 inches) | 66% | very high |
| September Weather | 12°C (54°F) | 30 mm (1.2 inches) | 66% | very high |
| October Weather | 3°C (37°F) | 42 mm (1.7 inches) | 77% | high |
| November Weather | -3°C (27°F) | 34 mm (1.3 inches) | 91% | moderate |
| December Weather | -9°C (16°F) | 38 mm (1.5 inches) | 96% | low |