Last updated: June 24, 2025
In December, the average temperature in Mason City, United States hovers around -3°C (27°F), with extremes ranging from a chilly -23°C (-9°F) to a surprisingly warm 20°C (68°F). During this month, expect around 35 mm (1.4 in) of precipitation spread over 5 days, accompanied by a high average humidity of 83%. Stay prepared for a diverse weather experience!
In December in Mason City, the average temperature is -3°C (27°F). Maximum temperatures can reach 20°C (68°F), while minimums can drop as low as -23°C (-9°F). Travelers should be prepared for a wide temperature range and pack accordingly for both chilly and warmer conditions.
In Mason City in December, the precipitation amount is 35 mm (1.4 in) over a span of 5 days.
In Mason City in December humidity is 83%. With an average temperature of -3°C (27°F), this humidity feels like a biting chill that wraps around you, making every breath feel heavy and the air almost damp with cold. Traveling in such conditions can be quite challenging, as the moisture in the air makes the cold penetrate deeper, making it essential to dress warmly and stay active to ward off the chill.
In Mason City 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 Mason City, you can check the information here.
UV Risk Categories
Weather in Mason City varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Mason City, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -8°C (19°F) | 36 mm (1.4 inches) | 82% | moderate |
| February Weather | -8°C (18°F) | 47 mm (1.9 inches) | 84% | moderate |
| March Weather | 1°C (35°F) | 71 mm (2.8 inches) | 80% | moderate |
| April Weather | 7°C (45°F) | 80 mm (3.1 inches) | 81% | very high |
| May Weather | 15°C (60°F) | 159 mm (6.3 inches) | 74% | very high |
| June Weather | 22°C (72°F) | 132 mm (5.2 inches) | 80% | extreme |
| July Weather | 23°C (74°F) | 98 mm (3.8 inches) | 80% | very high |
| August Weather | 21°C (71°F) | 118 mm (4.7 inches) | 77% | very high |
| September Weather | 18°C (65°F) | 108 mm (4.2 inches) | 75% | very high |
| October Weather | 10°C (49°F) | 112 mm (4.4 inches) | 80% | moderate |
| November Weather | 1°C (35°F) | 49 mm (1.9 inches) | 87% | moderate |
| December Weather | -3°C (27°F) | 35 mm (1.4 inches) | 83% | moderate |