Last updated: June 24, 2025
In December, the average temperature in Boston, United States hovers around 8°C (47°F), with temperatures ranging from a chilly -4°C (24°F) to a warm 18°C (65°F). Expect 102 mm (4.0 in) of precipitation spread over roughly 10 days, contributing to an average humidity level of 84%. Be prepared for cool, damp weather as you explore this beautiful destination!
In December in Boston, the average temperature is 8°C (47°F), with a maximum reaching 18°C (65°F) and a minimum dropping as low as -4°C (24°F). It's advisable to pack layers and be prepared for a range of temperatures while exploring this destination.
In Boston in December, the total precipitation amount is 102 mm (4.0 in) falling over the course of 10 days.
In Boston in December, humidity is 84%. With an average temperature of 8°C (47°F), this humidity feels like a damp blanket wrapping around you, making travel feel heavy and a bit lethargic, as the air thickens with moisture and each step becomes a little more cumbersome.
In Boston 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 Boston, you can check the information here.
UV Risk Categories
Weather in Boston varies notably across the year, with each month offering distinct climate conditions. This page compares December’s weather to other months in Boston, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 5°C (41°F) | 94 mm (3.7 inches) | 84% | moderate |
| February Weather | 6°C (43°F) | 119 mm (4.7 inches) | 83% | moderate |
| March Weather | 8°C (47°F) | 87 mm (3.4 inches) | 82% | high |
| April Weather | 13°C (55°F) | 86 mm (3.4 inches) | 81% | very high |
| May Weather | 17°C (64°F) | 89 mm (3.5 inches) | 80% | very high |
| June Weather | 23°C (73°F) | 73 mm (2.9 inches) | 82% | very high |
| July Weather | 26°C (79°F) | 107 mm (4.2 inches) | 81% | extreme |
| August Weather | 26°C (78°F) | 104 mm (4.1 inches) | 81% | very high |
| September Weather | 23°C (75°F) | 105 mm (4.1 inches) | 78% | very high |
| October Weather | 19°C (67°F) | 108 mm (4.2 inches) | 80% | high |
| November Weather | 12°C (54°F) | 91 mm (3.6 inches) | 84% | moderate |
| December Weather | 8°C (47°F) | 102 mm (4.0 inches) | 84% | moderate |