Last updated: June 24, 2025
In Mertztown, United States, the average temperature in December hovers around 3°C (37°F), with a minimum dipping to -14°C (6°F) and a maximum reaching 18°C (64°F). Expect around 101 mm (4.0 in) of precipitation spread over 10 days, and brace yourself for a high average humidity of 85%. Whether you’re exploring the chilly outdoors or cozying up inside, be prepared for a blend of brisk weather and moisture!
In December in Mertztown, the average temperature is 3°C (37°F). Maximums can reach 18°C (64°F), while minimums can drop as low as -14°C (6°F). Be prepared for a wide range of temperatures when traveling to Mertztown during this time.
In Mertztown in December, the precipitation amount is 101 mm (4.0 in) spread over the course of 10 days.
In Mertztown in December, humidity is 85%. With an average temperature of 3°C (37°F), this humidity feels like a chilling blanket enveloping you, making traveling uncomfortable as your clothes cling to your skin and the cold air bites at your face.
In Mertztown 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 Mertztown, you can visit Hourly UV Index in Mertztown.
UV Risk Categories
Weather in Mertztown varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Mertztown, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 0°C (33°F) | 69 mm (2.7 inches) | 87% | moderate |
| February Weather | 2°C (36°F) | 106 mm (4.2 inches) | 85% | moderate |
| March Weather | 5°C (42°F) | 100 mm (3.9 inches) | 85% | high |
| April Weather | 11°C (52°F) | 105 mm (4.1 inches) | 83% | very high |
| May Weather | 17°C (63°F) | 132 mm (5.2 inches) | 75% | very high |
| June Weather | 22°C (72°F) | 101 mm (4.0 inches) | 73% | very high |
| July Weather | 25°C (78°F) | 130 mm (5.1 inches) | 65% | very high |
| August Weather | 24°C (75°F) | 135 mm (5.3 inches) | 62% | very high |
| September Weather | 20°C (69°F) | 100 mm (3.9 inches) | 66% | very high |
| October Weather | 15°C (59°F) | 105 mm (4.1 inches) | 79% | high |
| November Weather | 6°C (44°F) | 89 mm (3.5 inches) | 87% | moderate |
| December Weather | 3°C (37°F) | 101 mm (4.0 inches) | 85% | low |