Last updated: June 24, 2025
In December, the average temperature in Harleysville, United States hovers around 3°C (38°F). Expect chilly conditions, with minimum temperatures dipping to -15°C (6°F) and soaring to a maximum of 18°C (65°F). Rainfall is fairly common, with 101 mm (4.0 in) of precipitation spread over about 10 days, contributing to an average humidity of 85%. Stay prepared for a wet and cool month!
In December in Harleysville, the average temperature is 3°C (38°F). Maximums can reach 18°C (65°F), while minimums can drop as low as -15°C (6°F). Be prepared for a wide range of temperatures when traveling during this month.
In Harleysville in December, the precipitation amount is 101 mm (4.0 in) spread over the course of 10 days.
In Harleysville in December, humidity is 85%. With an average temperature of 3°C (38°F), this humidity feels like a damp chill that seeps into your bones, making outdoor activities uncomfortable and travel less enjoyable as you contend with the heavy, cold air surrounding you.
In Harleysville 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 Harleysville, you can visit Hourly UV Index in Harleysville.
UV Risk Categories
Weather in Harleysville varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Harleysville, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 1°C (34°F) | 67 mm (2.7 inches) | 87% | moderate |
| February Weather | 3°C (37°F) | 106 mm (4.2 inches) | 85% | moderate |
| March Weather | 6°C (43°F) | 105 mm (4.1 inches) | 85% | high |
| April Weather | 12°C (53°F) | 104 mm (4.1 inches) | 83% | very high |
| May Weather | 17°C (63°F) | 144 mm (5.7 inches) | 75% | very high |
| June Weather | 22°C (72°F) | 111 mm (4.4 inches) | 73% | very high |
| July Weather | 25°C (78°F) | 147 mm (5.8 inches) | 65% | very high |
| August Weather | 24°C (75°F) | 163 mm (6.4 inches) | 62% | very high |
| September Weather | 21°C (69°F) | 100 mm (4.0 inches) | 66% | very high |
| October Weather | 15°C (60°F) | 102 mm (4.0 inches) | 79% | high |
| November Weather | 7°C (45°F) | 86 mm (3.4 inches) | 87% | moderate |
| December Weather | 3°C (38°F) | 101 mm (4.0 inches) | 85% | low |