Last updated: June 24, 2025
In December, the average temperature in Janesville, United States hovers around -1°C (31°F), with minimums plunging to -14°C (7°F) and maximums reaching 13°C (55°F). Expect 75 mm (3.0 in) of precipitation spread over 9 days, accompanied by a high average humidity of 86%. Stay prepared for chilly and damp conditions!
In December in Janesville, the average temperature is -1°C (31°F), with a maximum that can reach 13°C (55°F) and a minimum that can drop as low as -14°C (7°F). Travelers should be prepared for a wide temperature range and bring appropriate clothing for both cold and mild conditions.
In Janesville in December, the precipitation amount is 75 mm (3.0 in) distributed over 9 days.
In Janesville in December humidity is 86%. With an average temperature of -1°C (31°F), this humidity feels like an eerie chill enveloping you, making travel uncomfortable as the damp air bites into your skin and the cold seeps through even the warmest of clothes, creating an atmosphere that is heavy and uninviting.
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 | 0°C (32°F) | 102 mm (4.0 inches) | 86% | moderate |
| February Weather | 0°C (32°F) | 110 mm (4.3 inches) | 87% | moderate |
| March Weather | 2°C (37°F) | 85 mm (3.4 inches) | 86% | very high |
| April Weather | 8°C (46°F) | 43 mm (1.7 inches) | 83% | very high |
| May Weather | 12°C (55°F) | 44 mm (1.7 inches) | 72% | extreme |
| June Weather | 19°C (66°F) | 10 mm (0.4 inches) | 67% | extreme |
| July Weather | 23°C (74°F) | 7 mm (0.3 inches) | 56% | extreme |
| August Weather | 22°C (72°F) | 8 mm (0.3 inches) | 42% | extreme |
| September Weather | 17°C (63°F) | 19 mm (0.7 inches) | 46% | very high |
| October Weather | 10°C (50°F) | 34 mm (1.3 inches) | 67% | high |
| November Weather | 4°C (40°F) | 47 mm (1.8 inches) | 86% | moderate |
| December Weather | -1°C (31°F) | 75 mm (3.0 inches) | 86% | moderate |