Last updated: June 24, 2025
In December, the average temperature in Mendham, United States hovers around 3°C (37°F). Expect chilly nights, with minimum temperatures dipping as low as -13°C (9°F), while the days can warm up to a pleasant 18°C (64°F). Be prepared for some rain, as precipitation totals around 113 mm (4.4 in) over about 10 days. With an average humidity of 80%, the air will feel quite moist, so it's wise to dress in layers!
In December in Mendham, the average temperature is 3°C (37°F). Maximum temperatures can reach 18°C (64°F), while minimums can drop as low as -13°C (9°F). Be prepared for a wide range of temperatures when traveling during this time.
In Mendham in December, the total precipitation amount is 113 mm (4.4 in) over a span of 10 days.
In Mendham in December, humidity is 80%. With an average temperature of 3°C (37°F), this humidity feels like a damp blanket wrapping around you, making outdoor adventures less enjoyable and prompting you to seek cozy indoor activities instead.
In Mendham 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 Mendham, you can visit Hourly UV Index in Mendham.
UV Risk Categories
Weather in Mendham varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Mendham, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 0°C (33°F) | 70 mm (2.7 inches) | 84% | moderate |
| February Weather | 2°C (36°F) | 104 mm (4.1 inches) | 82% | moderate |
| March Weather | 5°C (41°F) | 103 mm (4.1 inches) | 81% | high |
| April Weather | 11°C (52°F) | 116 mm (4.6 inches) | 78% | very high |
| May Weather | 16°C (62°F) | 135 mm (5.3 inches) | 69% | very high |
| June Weather | 21°C (71°F) | 106 mm (4.2 inches) | 69% | very high |
| July Weather | 25°C (77°F) | 142 mm (5.6 inches) | 62% | very high |
| August Weather | 24°C (75°F) | 136 mm (5.4 inches) | 65% | very high |
| September Weather | 20°C (69°F) | 101 mm (4.0 inches) | 68% | very high |
| October Weather | 15°C (59°F) | 142 mm (5.6 inches) | 74% | high |
| November Weather | 7°C (44°F) | 86 mm (3.4 inches) | 82% | moderate |
| December Weather | 3°C (37°F) | 113 mm (4.4 inches) | 80% | low |