Boston Weather in December

Boston, Massachusetts usually experiences its first truly wintery weather of the season in December. Winter snowstorms are common and so too days when the temperature remains below freezing.

This page gives detailed information on the typical December temperature, precipitation, sun, humidity, wind and storms for Boston. The numbers here are historical averages based on climate data gathered at Boston's Logan International Airport, located on the waterfront next to Boston Harbor.

Temperature

42 °F	December average high	6 °C
29 °F	December average low	-2 °C

19 days	40 °F max. or more (4 °C)
20 days	32 °F min. or less (0 °C)

Boston averages one day in December when the thermometer reaches into the 60s Fahrenheit (over 15 degrees Celsius). A temperature above 70 °F (21 °C) in December has happened about once a decade. Typically on 4 days the mercury remains below freezing for the entire day.

In some years, December will have a night that drops to 10 °F (-12 °C) or below. But the weather does not normally get as cold as 0 °F (-18 °C).

Precipitation

4.3 in	total precipitation	109 mm
12 days	of rain or snowfall

Half the time, Boston receives 2.8 to 5.6 inches (72 to 142 mm) of precipitation in December. One in four years has drier weather, while another one in four is wetter.

Snow

9.0 in	total snowfall	23 cm
4 days	with new snow

December's snowfall varies a lot from year to year in Boston. Between 1.5 and 12 inches (4 to 29 cm) of fresh snow arrives in half the years. Less new snow lands in one out of four Decembers, while another twenty-five percent are snowier.

Sun

52 %	sunshine
9 days	clear skies

The sun's rays reach the ground in Boston during 52 percent of daylight hours on average in December, for a total of 147 hours in the month. Typically on 9 days this month the sky is mainly clear, with at most 30 percent cloud cover.

Sunlight in December at Boston lasts for 9 hours and 8 minutes a day on average. The shortest days of the year, from around December 18th to 24th, last 9 hours and 5 minutes from sunrise to sunset.

Humidity

65 %	December average humidity

The relative humidity in Boston during December usually peaks at 71 percent in the morning then drops to 59 percent by early afternoon.

Local Time	1 am	4 am	7 am	10 am	1 pm	4 pm	7 pm	10 pm
Humidity %	68	70	71	65	59	60	64	66

Wind

13.2 mph

December wind speed average

21.2 kph

December is a little windier than most other months in Boston.

Storms

1 day	snowfall of 3 inches (8 cm) or more
0 days	with thunderstorms in December

The first substantial snowfalls of winter for Boston usually arrive in December.

About once in five years, a December thunderstorm passes over Boston.