Last updated: June 24, 2025
In December, the average temperature in Hartley, United States hovers around -3°C (27°F). Expect minimums to plummet to -24°C (-10°F), while the mercury can rise to a maximum of 18°C (65°F). This month also sees 39 mm (1.5 in) of precipitation spread over about 4 days, coupled with a relatively high average humidity of 83%.
In December in Hartley, the average temperature is -3°C (27°F), with maximums reaching up to 18°C (65°F) and minimums plummeting to as low as -24°C (-10°F). Travelers should be prepared for a wide range of temperatures and pack accordingly for both chilly and mild conditions.
In Hartley in December, the precipitation amount is 39 mm (1.5 in) spread over a period of 4 days.
In Hartley 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 Hartley 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 Hartley, you can check the information here.
UV Risk Categories
Weather in Hartley varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Hartley, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -7°C (20°F) | 28 mm (1.1 inches) | 80% | moderate |
| February Weather | -7°C (19°F) | 34 mm (1.3 inches) | 84% | moderate |
| March Weather | 2°C (35°F) | 69 mm (2.7 inches) | 75% | moderate |
| April Weather | 7°C (45°F) | 101 mm (4.0 inches) | 79% | very high |
| May Weather | 15°C (59°F) | 136 mm (5.3 inches) | 74% | very high |
| June Weather | 22°C (72°F) | 126 mm (5.0 inches) | 81% | extreme |
| July Weather | 24°C (75°F) | 73 mm (2.9 inches) | 82% | very high |
| August Weather | 22°C (71°F) | 104 mm (4.1 inches) | 80% | very high |
| September Weather | 19°C (66°F) | 109 mm (4.3 inches) | 75% | very high |
| October Weather | 9°C (49°F) | 88 mm (3.5 inches) | 77% | moderate |
| November Weather | 2°C (35°F) | 31 mm (1.2 inches) | 85% | moderate |
| December Weather | -3°C (27°F) | 39 mm (1.5 inches) | 83% | moderate |