December weather forecast
Waltham, MA

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Weather in December

Finally, December signifies the onset of winter in Waltham, Massachusetts. With scarce daylight hours and temperature plummeting, this month sets to adopt the winter mode in all its glory. Slightly lower than November, the high for December is 39.2°F (4°C) and the low falls at 28.6°F (-1.9°C). The fresh snow blankets the city, creating a picturesque winter wonderland to conclude the climatic cycle.

Temperature

December's arrival coincides with a drop in the average high-temperature, decreasing from November's chilly 49.1°F (9.5°C) to an icy 39.2°F (4°C). Waltham's temperature drops to an average low of 28.6°F (-1.9°C) during the nights of December.

Humidity

The average relative humidity in December is 77%.

Rainfall

In December, in Waltham, the rain falls for 6.6 days. Throughout December, 0.79" (20mm) of precipitation is accumulated. Throughout the year, in Waltham, there are 106.3 rainfall days, and 8.5" (216mm) of precipitation is accumulated.

Snowfall

Months with snowfall are January through May, November and December. The month with the most snowfall in Waltham is December, when snow falls for 3.1 days and typically aggregates up to 1.14" (29mm) of snow.

Daylight

December has the shortest days of the year, with an average of 9h and 6min of daylight.
On the first day of the month, sunrise is at 6:55 am and sunset at 4:13 pm. On the last day of December, in Waltham, sunrise is at 7:14 am and sunset at 4:22 pm EST.

Sunshine

The average sunshine in December is 5h.

UV index

The months with the lowest UV index in Waltham are January through March, November and December, with an average maximum UV index of 2. A UV Index of 2, and less, symbolizes a low health risk from unprotected exposure to Sun's UV rays for the average person.
Note: In December, the average maximum UV index of 2 translates into the following recommendations:
Prolonged sun exposure should always be prevented in babies, children, and those with sensitive skin. The Sun's harshest UV rays are around midday; it's wise to seek shade and limit time outdoors. Safeguard your eyes, ears, and face from sun rays with the aid of a wide-brim hat. Remember this! The UV radiation of the Sun can be nearly doubled by the reflective properties of snow.
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Frequently asked questions

How cold is it in Waltham in December?

In December, the average high-temperature and low-temperature in Waltham, Massachusetts, are 39.2°F (4°C) and 28.6°F (-1.9°C) respectively. In August, the average heat index (a.k.a. 'real feel', 'feels like'), which combines air temperature and relative humidity, is evaluated at 84.2°F (29°C).

What is the average humidity in December in Waltham?

In December, the average relative humidity in Waltham, Massachusetts, is 77%.

How much does it rain in Waltham in December?

In December, in Waltham, Massachusetts, the rain falls for 6.6 days. Throughout December, 0.79" (20mm) of precipitation is accumulated.

What is the snowiest month in Waltham?

The month with the most snowfall in Waltham is December, when snow falls for 3.1 days and typically aggregates up to 1.14" (29mm) of snow.

How much does it snow in Waltham in December?

In Waltham, Massachusetts, in December, during 3.1 snowfall days, 1.14" (29mm) of snow is typically accumulated.

What is the month with the shortest days in Waltham?

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

How many hours of daylight does Waltham have in December?

In December, the average day length in Waltham is 9h and 8min.

When are sunrise and sunset in December in Waltham?

In December, on the first day of the month, sunrise is at 6:55 am and sunset at 4:13 pm. On the last day of the month, in Waltham, Massachusetts, sunrise is at 7:14 am and sunset at 4:22 pm EST.

How many hours of sunshine does Waltham have in December?

In Waltham, Massachusetts, the average sunshine duration in December is 5h.

What is the month with the lowest UV index in Waltham?

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

How high is the UV index in December in Waltham?

The average daily maximum UV index in December is 2. A UV Index value of 2, and less, symbolizes a minimal hazard to health from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
Waltham, MA

Average temperature in December - Waltham, MA
  • Average high temperature in December: 39.2°F

The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (33.3°F).

  • Average low temperature in December: 28.6°F

The month with the highest average low temperature is July (64°F).
The coldest month (with the lowest average low temperature) is January (21.6°F).

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Average pressure in December
Waltham, MA

Average pressure in December - Waltham, MA
  • Average pressure in December: 30.03"Hg

The month with the highest atmospheric pressure is November (30.07"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

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Average wind speed in December
Waltham, MA

Average wind speed in December - Waltham, MA
  • Average wind speed in December: 8.5mph

The windiest month (with the highest average wind speed) is January (9.1mph).
The calmest month (with the lowest average wind speed) is August (5.8mph).

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Average humidity in December
Waltham, MA

Average humidity in December - Waltham, MA
  • Average humidity in December: 77%

The month with the highest relative humidity is February (78%).
The month with the lowest relative humidity is April (70%).

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Average rainfall in December
Waltham, MA

Average rainfall in December - Waltham, MA
  • Average rainfall in December: 0.79"

The wettest months (with the highest rainfall) are April and November (0.87").
The driest month (with the least rainfall) is September (0.35").

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Average rainfall days in December
Waltham, MA

Average rainfall days in December - Waltham, MA
  • Average rainfall days in December: 6.6 days

The month with the highest number of rainy days is July (12.4 days).
The month with the least rainy days is January (5.3 days).

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Average snowfall in December
Waltham, MA

Average snowfall in December - Waltham, MA
  • Average snowfall in December: 1.14"

The month with the highest snowfall is December (1.14").
The months with the least snowfall are June, July, August, September and October (0").

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Average snowfall days in December
Waltham, MA

Average snowfall days in December - Waltham, MA
  • Average snowfall days in December: 3.1 days

The month with the highest number of snowfall days is February (5.4 days).
The months with the least snowfall days are June, July, August, September and October (0 days).

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Average daylight in December /
Average sunshine in December
Waltham, MA

Average daylight in December / Average sunshine in December - Waltham, 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: 5h and 0min

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 42min).

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Average sunshine days in December
Waltham, MA

Average sunshine days in December - Waltham, MA
  • Average sunshine days in December: 21.4 days

The month with the most sunshine days is January (22.2 days).
The month with the least sunshine days is June (15.8 days).

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Average UV index in December
Waltham, MA

Average UV index in December - Waltham, 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).

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Average cloud cover in December
Waltham, MA

Average cloud cover in December - Waltham, MA
  • Average cloud cover in December: 46

The month with the most cloud cover is March (Cloud cover 50).
The month with the least cloud cover is August (Cloud cover 32).

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Average visibility in December
Waltham, MA

Average visibility in December - Waltham, 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).

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Waltham, Massachusetts, USA

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