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December Weather in Boston, United States

Last updated: June 24, 2025

In Boston, United States, the average temperature in December hovers around 13°C (56°F), with a minimum dipping to -4°C (25°F) and a maximum soaring to 27°C (81°F). Expect about 117 mm (4.6 in) of precipitation spread over 9 days, contributing to a high average humidity of 88%.

December Temperature in Boston

In December, in Boston, the average temperature is 13°C (56°F). Maximums can reach 27°C (81°F), while minimums can dip as low as -4°C (25°F). Travelers should be prepared for a wide range of temperatures and pack appropriately for both warm and cool conditions.

December Weather in Boston: Daily Temperature Highs, Lows, and Averages

The chart illustrates December temperature patterns in Boston, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Boston, December typically has an average temperature of 13°C (56°F), with highs reaching up to 27°C (81°F) and lows dropping to around -4°C (25°F).
JanFebMarAprMayJunJulAugSepOctNovDec535963687680818180736056
Data source: Temperature data for Boston generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

December Precipitation in Boston

In Boston in December, the total precipitation amount is 117 mm (4.6 in) spread over a period of 9 days.

December Precipitation Trends in Boston

The chart displays monthly precipitation patterns in Boston, with values for each month alongside December’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how December’s conditions compare to those of other months. In Boston, December typically receives around 117 mm (4.6 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec72965280741571481371107350118
Data source: Precipitation data for December generated using information from the Copernicus Climate Change Service.
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December Humidity in Boston

In Boston in December, humidity is 88%. With an average temperature of 13°C (56°F), this humidity feels like a thick, warm blanket wrapping around you, making outdoor adventures sticky and challenging.

December Average Humidity in Boston

This chart illustrates the average monthly humidity levels in Boston, with December’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In December, average humidity in Boston is approximately 88%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec85%82%80%76%73%74%80%79%83%77%84%88%
Data source: Humidity data for December generated using information from the Copernicus Climate Change Service.

December UV Index in Boston

In Boston in December, the maximum UV index reaches 4, which corresponds to a moderate Exposure Category. With a time to burn of 30 minutes, it’s important to take precautions to protect your skin. You can find more details in the Hourly UV Index in Boston for better planning.

Maximum UV Index Levels in Boston for December

The chart shows the monthly maximum UV Index (UVI) for Boston in December, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In December, the maximum UV index in Boston typically reaches 4, which falls under the moderate exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec589101111111110864
Data source: Boston December UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How December Weather in Boston Compares to Other Months

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.

This table compares monthly weather conditions in Boston, showing how December’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather12°C (54°F)72 mm (2.8 inches)85%moderate
February Weather15°C (60°F)96 mm (3.8 inches)82%very high
March Weather17°C (64°F)52 mm (2.1 inches)80%very high
April Weather20°C (69°F)80 mm (3.1 inches)76%very high
May Weather25°C (76°F)74 mm (2.9 inches)73%extreme
June Weather27°C (80°F)157 mm (6.2 inches)74%extreme
July Weather27°C (81°F)148 mm (5.8 inches)80%extreme
August Weather27°C (82°F)137 mm (5.4 inches)79%extreme
September Weather26°C (80°F)110 mm (4.3 inches)83%very high
October Weather23°C (74°F)73 mm (2.9 inches)77%very high
November Weather16°C (61°F)50 mm (2.0 inches)84%high
December Weather13°C (56°F)117 mm (4.6 inches)88%moderate

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