December weather forecast and climate
Boston, MA

A beautiful natural park with the George Washington Monument in Boston, Massachusetts, with a sneak view of the city skyscrapers
A beautiful natural park with the George Washington Monument in Boston, Massachusetts, with a sneak view of the city skyscrapers
Winter brings freezing weather to Boston in December, with the temperature dropping further to the range of 28.2°F (-2.1°C) and 41.2°F (5.1°C). The temperature at night drops to as low as 23°F (-5°C) and the cold waves experienced occasionally make the weather feel colder than registered.
Snowfall is more significant and is experienced for approximately five days to collect 9" (228.6mm) on the ground. Rainfall in December falls for eleven and a half days, and the rain gauge meters read 3.8" (96.5mm) in precipitation.
Basking in the four and a half hours of sunshine is usual, and activities may include skating and skiing. Most other outdoor activities are paused as winter goes on.

What is the temperature in December in Boston?

The average high-temperature, in December, is 41.2°F (5.1°C), while the average low-temperature is 28.2°F (-2.1°C).

How much does it rain in Boston in December?

In Boston, Massachusetts, during December, the rain falls for 11.6 days and regularly aggregates up to 3.8" (96mm) of precipitation.

How many days does it snow in December in Boston?

In Boston, Massachusetts, in December, snow falls for 4.6 days, with typically accumulated 9" (228.6mm) of snow.

What is the sea water temperature in December in Boston?

The average seawater temperature, in December, in Boston, Massachusetts, is 46.8°F (8.2°C). Swimming in 46.8°F (8.2°C) is considered dangerous. Unprotected immersion in temperatures below 50°F (10°C) causes quickly maximum intensity cold shock with hyperventilation.
Average temperature in December - Boston, MA
  • Average high temperature in December: 41.2°F

The warmest month (with the highest average high temperature) is July (81.4°F).
The month with the lowest average high temperature is January (35.8°F).

  • Average low temperature in December: 28.2°F

The month with the highest average low temperature is July (65.4°F).
The coldest month (with the lowest average low temperature) is January (22.2°F).

Average humidity in December - Boston, MA
  • Average humidity in December: 65.4%

The month with the highest relative humidity is September (71.8%).
The month with the lowest relative humidity is February (62%).

Average rainfall in December - Boston, MA
  • Average rainfall in December: 3.8"

The wettest month (with the highest rainfall) is March (4.3").
The driest month (with the lowest rainfall) is February (3.3").

Average rainfall days in December - Boston, MA
  • Average rainfall days in December: 11.6 days

The month with the highest number of rainy days is May (12 days).
The month with the lowest number of rainy days is September (8.6 days).

Average snowfall in December - Boston, MA
  • Average snowfall in December: 9"

The month with the highest snowfall is January (12.9").
Months with the lowest snowfall are May, June, July, August, September and October (0").

Average snowfall days in December - Boston, MA
  • Average snowfall days in December: 4.6 days

The month with the highest number of snowfall days is January (6.7 days).
Months with the lowest number of snowfall days are May, June, July, August and September (0 days).

Average sea temperature in December - Boston, MA
  • Average sea temperature in December: 46.6°F

The best month for swimming (with the highest average sea temperature) is August (67.9°F).
The coldest month (with the lowest average sea temperature) is February (38.1°F).

Average daylight in December / Average sunshine in December - Boston, MA
  • Average daylight in December: 9.1h

The month with the longest days is June (Average daylight: 15.2h).
The month with shortest days is December (Average daylight: 9.1h).

  • Average sunshine in December: 4.6h

The month with most sunshine is July (Average sunshine: 9.7h).
The month with least sunshine is December (Average sunshine: 4.6h).

Average UV index in December - Boston, MA
  • Average UV index in December: 1

Months with the highest UV index are June, July and August (UV index 8).
Months with the lowest UV index are January and December (UV index 1).

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