Last updated: June 24, 2025
In Janesville, United States, the average temperature in December hovers around -4°C (25°F), with a minimum dipping as low as -24°C (-11°F) and a maximum reaching up to 19°C (66°F). This month typically sees 44 mm (1.7 in) of precipitation spread over about 5 days, resulting in a high average humidity of 83%. Be prepared for a chilly, damp atmosphere!
In December in Janesville, the average temperature is -4°C (25°F), with maximums reaching 19°C (66°F) and minimums plunging as low as -24°C (-11°F). Travelers should be prepared for a wide range of temperatures and dress accordingly to ensure comfort during their visit.
In Janesville in December, the precipitation amount is 44 mm (1.7 in) over the course of 5 days.
In Janesville in December, humidity is 83%. With an average temperature of -4°C (25°F), this humidity feels like a chilling fog enveloping you, making every breath feel heavy and damp, which can quickly dampen the spirit of travel as you navigate the frosty landscape.
In Janesville 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 Janesville, you can check the information here.
UV Risk Categories
Weather in Janesville varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Janesville, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -8°C (17°F) | 34 mm (1.3 inches) | 82% | moderate |
| February Weather | -9°C (17°F) | 41 mm (1.6 inches) | 84% | moderate |
| March Weather | 1°C (34°F) | 68 mm (2.7 inches) | 80% | moderate |
| April Weather | 7°C (45°F) | 91 mm (3.6 inches) | 81% | very high |
| May Weather | 15°C (60°F) | 140 mm (5.5 inches) | 74% | very high |
| June Weather | 22°C (72°F) | 118 mm (4.7 inches) | 80% | very high |
| July Weather | 23°C (74°F) | 103 mm (4.1 inches) | 80% | very high |
| August Weather | 21°C (71°F) | 119 mm (4.7 inches) | 77% | very high |
| September Weather | 18°C (65°F) | 137 mm (5.4 inches) | 75% | very high |
| October Weather | 9°C (49°F) | 93 mm (3.7 inches) | 80% | moderate |
| November Weather | 1°C (35°F) | 36 mm (1.4 inches) | 87% | moderate |
| December Weather | -4°C (25°F) | 44 mm (1.7 inches) | 83% | moderate |