December weather - Winter 2024

Weather in December
Frequently asked questions
Average temperature in December
Average pressure in December
Average wind speed in December
Average humidity in December
Average rainfall in December
Average rainfall days in December
Average snowfall in December
Average snowfall days in December
Average sea temperature in December
Average daylight in December
Average sunshine in December
Average sunshine days in December
Average UV index in December
Average cloud cover in December
Average visibility in December

A beautiful natural park with the George Washington Monument in Boston, Massachusetts

Weather in December

For Boston, December is synonymous with winter, and the climatic conditions validate this perception. A considerable drop in temperatures from November's mildness indicates a high of 39.9°F (4.4°C) and a low of 29.7°F (-1.3°C). This time, the city gets smothered in holiday spirit, with sparkling lights lining the streets and festive decorations adorning houses. Despite the cold weather, the warmth of Christmas and New Year's Eve celebrations bring a cheer and joviality to the overall atmosphere.

Temperature

The shift to December brings a decrease in the average high-temperature, falling from a chilly 49.5°F (9.7°C) in November to a wintry 39.9°F (4.4°C). Boston in December anticipates an average nighttime temperature of 29.7°F (-1.3°C).

Humidity

The average relative humidity in December is 76%.

Rainfall

The months with the most rainfall are March, April and December, with an average 2.91" (74mm) of precipitation.

Snowfall

Months with snowfall are January through May, October through December. In Boston, during December, snow falls for 5.2 days and regularly aggregates up to 2.83" (72mm) of snow. In Boston, during the entire year, snow falls for 29.8 days and aggregates up to 15.75" (400mm) of snow.

Ocean temperature

In Boston, the average seawater temperature in December is 46.8°F (8.2°C).
Note: It is life-risking to swim in 46.8°F (8.2°C). Briefly staying in 55.4°F (13°C) waters feels unsettling, and temperatures below 50°F (10°C) might result in cold shock and loss of breath control, hinging on personal endurance.

Daylight

The month with the shortest days is December, with an average of 9h and 6min of daylight.
On the first day of the month, sunrise is at 6:54 am and sunset at 4:12 pm. On the last day of December, sunrise is at 7:13 am and sunset at 4:21 pm EST.

Sunshine

In December, the average sunshine is 4.7h.

UV index

January through March, November and December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index of 2, and less, symbolizes a minimal health vulnerability from exposure to the Sun's UV rays for ordinary individuals.
Note: The UV index of 2 during December leads to these advisories:
Most individuals face no major issues with lengthy exposure to the sun, but children, infants, and individuals with fair skin always require protection. UV radiation is strongest from the Sun during midday; protect yourself by staying in shaded areas. Tightly woven clothing, when worn loosely, shields effectively against the Sun. Note well! The intensity of the Sun's UV rays can be nearly doubled by snow reflection.

Updated: Jun 4, 2024
Published by: Weather Atlas | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

Is December cold?

The high-temperature, in December, in Boston, is 39.9°F (4.4°C), while the low-temperature averages to 29.7°F (-1.3°C). The average heat index (a.k.a. 'apparent temperature', 'felt air temperature'), which combines relative humidity and air temperature, in July is evaluated at 86°F (30°C).

What is the average humidity in December?

In December, the average relative humidity is 76%.

What is the wettest month?

The wettest months are March, April and December, with an average 2.91" (74mm) of rainfall.

How much does it rain in December?

In Boston, in December, during 10.1 rainfall days, 2.91" (74mm) of precipitation is typically accumulated.

How much does it snow in December?

In Boston, during December, snow falls for 5.2 days and regularly aggregates up to 2.83" (72mm) of snow.

What is the water temperature in December?

In December, the average ocean temperature is 46.8°F (8.2°C). At temperatures below 50°F (10°C), swimming in a suitably protected swimsuit is feasible; otherwise, cold shock and loss of breathing control are imminent. Even a short swim, without thermal protection, at temperatures around 55.4°F (13°C) is not comfortable.

What is the month with the shortest days?

With an average of 9h and 6min of daylight, December has the shortest days of the year.

How many hours of daylight does Boston have in December?

The average day length in December is 9h and 8min.

What time are sunrise and sunset in December?

On the first day of December, sunrise is at 6:54 am and sunset at 4:12 pm. On the last day of the month, sunrise is at 7:13 am and sunset at 4:21 pm EST.

How many hours of sunshine does Boston have in December?

The average sunshine duration in December is 4.7h.

When is the lowest UV index?

January through March, November and December, with an average maximum UV index of 2, are months with the lowest UV index.

What is the UV index reading in December in Boston?

In December, the average daily maximum UV index is 2. A UV Index value of 2, and less, symbolizes a minimal hazard to health from unprotected exposure to UV radiation.

Today

Tomorrow

Long-term

Year J F M A M J J A S O N December

Nov

December

Jan

Average high temperature

49.5°F 9.7°C

39.9°F 4.4°C

34.2°F 1.2°C

Average low temperature

Average pressure

Average wind speed

Average max. wind speed

9.4mph 15.1km/h

10.1mph 16.3km/h

10.5mph 16.9km/h

Average wind speed gusts

Average humidity

Average rainfall

Average rainfall days

Average snowfall

Average snowfall days

1.4

5.2

7.6

Average sea temperature

Average daylight

Average sunshine

Average sunshine days

17.5

16.5

17.5

Average UV index

Average cloud cover

Average visibility

Average temperature in December
Boston, MA

Average high temperature in December: 39.9°F

The warmest month (with the highest average high temperature) is July (81.7°F).
The month with the lowest average high temperature is January (34.2°F).

Average low temperature in December: 29.7°F

The month with the highest average low temperature is July (64.9°F).
The coldest month (with the lowest average low temperature) is January (22.6°F).

Average pressure in December
Boston, MA

Average pressure in December: 30.03"Hg

The month with the highest atmospheric pressure is November (30.06"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).

Average wind speed in December
Boston, MA

Average wind speed in December: 9.4mph

The windiest month (with the highest average wind speed) is January (9.9mph).
The calmest month (with the lowest average wind speed) is August (6.2mph).

Average humidity in December
Boston, MA

Average humidity in December: 76%

The month with the highest relative humidity is February (77%).
The month with the lowest relative humidity is April (69%).

Average rainfall in December
Boston, MA

Average rainfall in December: 2.91"

The wettest months (with the highest rainfall) are March, April and December (2.91").
The driest month (with the least rainfall) is September (1.26").

Average rainfall days in December
Boston, MA

Average rainfall days in December: 10.1 days

The month with the highest number of rainy days is May (15.3 days).
The month with the least rainy days is January (7.9 days).

Average snowfall in December
Boston, MA

Average snowfall in December: 2.83"

The month with the highest snowfall is February (4.72").
The months with the least snowfall are June, July, August and September (0").

Average snowfall days in December
Boston, MA

Average snowfall days in December: 5.2 days

The months with the highest number of snowfall days are January and February (7.6 days).
The months with the least snowfall days are 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: 9h and 1min

The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 6min).

Average sunshine in December: 4h and 4min

The month with the most sunshine is August (Average sunshine: 10h and 30min).
The month with the least sunshine is February (Average sunshine: 4h and 36min).

Average sunshine days in December
Boston, MA

Average sunshine days in December: 16.5 days

The month with the most sunshine days is September (17.7 days).
The month with the least sunshine days is April (13 days).

Average UV index in December
Boston, MA

Average UV index in December: 2

The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, March, November and December (UV index 2).

Average cloud cover in December
Boston, MA

Average cloud cover in December: 48

The month with the most cloud cover is March (Cloud cover 51).
The month with the least cloud cover is August (Cloud cover 32).

Average visibility in December
Boston, MA

Average visibility in December: 6mi

The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).

December weather forecast
Boston, MA

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