December weather forecast
Onset, MA

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Weather in December

The first month of the winter, December, is still a cold month in Onset, Massachusetts, with an average temperature ranging between min 34.2°F (1.2°C) and max 42.4°F (5.8°C).

Temperature

With the arrival of December, Onset notices a mild change in the average high-temperature, sliding from November's fresh 50.9°F (10.5°C) to a wintry 42.4°F (5.8°C). Registering an almost steady temperature, Onset's nights in December see an average low of 34.2°F (1.2°C).

Humidity

In Onset, the average relative humidity in December is 76%.

Rainfall

December is the month with the most rainfall in Onset. Rain falls for 12.5 days and accumulates 3.58" (91mm) of precipitation.

Snowfall

January through April, October through December are months with snowfall in Onset. In Onset, in December, during 3.5 snowfall days, 1.26" (32mm) of snow is typically accumulated. Throughout the year, in Onset, there are 21.7 snowfall days, and 8.43" (214mm) of snow is accumulated.

Ocean temperature

In Onset, the average seawater temperature in December is 46.9°F (8.3°C).
Note: In 46.9°F (8.3°C), even brief exposure to 55.4°F (13°C) feels biting, and anything less than 50°F (10°C) risks cold shock and impaired breathing, considering one's health.

Daylight

December has the shortest days of the year, with an average of 9h and 12min of daylight.
On the first day of the month, sunrise is at 6:50 am and sunset at 4:12 pm. On the last day of December, sunrise is at 7:09 am and sunset at 4:22 pm EST.

Sunshine

The months with the least sunshine are February and December, with an average of 4.8h of sunshine.

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 radiation for the ordinary person.
Note: The daily maximum UV index of 2 in December interprets into the following advice:
People with sensitive skin, children, and babies should always be protected from prolonged sun exposure. Considering the strength of solar radiation at midday, one should avoid direct Sun exposure. For minimizing sun-related eye damage, always choose sunglasses with UVA and UVB coverage. Take warning! The intensity of the Sun's UV radiation can be nearly amplified twice due to snow reflection.
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Frequently asked questions

Is it cold in Onset during December?

Onset in December has an average high-temperature of 42.4°F (5.8°C) and an average low-temperature of 34.2°F (1.2°C).

What is the average humidity in December in Onset?

The average relative humidity in December in Onset, Massachusetts, is 76%.

What is the wettest month in Onset?

December is the month with the most rainfall in Onset. Rain falls for 12.5 days and accumulates 3.58" (91mm) of precipitation.

How many days does it rain in December in Onset?

In December, in Onset, the rain falls for 12.5 days. Throughout December, 3.58" (91mm) of precipitation is accumulated.

How many days does it snow in December in Onset?

In Onset, in December, during 3.5 snowfall days, 1.26" (32mm) of snow is typically accumulated.

What is the ocean temperature in December in Onset?

In Onset, Massachusetts, the average seawater temperature in December is 46.9°F (8.3°C). Swimming in 46.9°F (8.3°C) is considered life-threatening. Even a few minutes in 55.4°F (13°C) water is uncomfortable, and swimming below 50°F (10°C) may cause total loss of breathing control and cold shock, depending on a person's physique.

What is the month with the shortest days in Onset?

With an average of 9h and 12min of daylight, December has the shortest days of the year.

What is the average length of the day in December in Onset?

The average day length in December in Onset is 9h and 13min.

What time are sunrise and sunset in December in Onset?

In December, on the first day of the month, sunrise is at 6:50 am and sunset at 4:12 pm. On the last day of the month, in Onset, sunrise is at 7:09 am and sunset at 4:22 pm EST.

What are the months with the least sunshine in Onset?

February and December, with an average of 4.8h of sunshine, are months with the least sunshine in Onset.

How long on average sun shines in December in Onset?

In December, the average sunshine duration in Onset is 4.8h.

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

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

What is the UV index reading in December in Onset?

In December, the average daily maximum UV index in Onset, Massachusetts, is 2. A UV Index of 2, and less, symbolizes a low health risk 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
Onset, MA

Average temperature in December - Onset, MA
  • Average high temperature in December: 42.4°F

The warmest month (with the highest average high temperature) is July (75.6°F).
The month with the lowest average high temperature is January (36.9°F).

  • Average low temperature in December: 34.2°F

The month with the highest average low temperature is August (66.7°F).
The coldest month (with the lowest average low temperature) is January (27.7°F).

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Average pressure in December
Onset, MA

Average pressure in December - Onset, 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).

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Average wind speed in December
Onset, MA

Average wind speed in December - Onset, MA
  • Average wind speed in December: 13mph

The windiest month (with the highest average wind speed) is January (13.7mph).
The calmest month (with the lowest average wind speed) is August (8.7mph).

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Average humidity in December
Onset, MA

Average humidity in December - Onset, MA
  • Average humidity in December: 76%

The months with the highest relative humidity are June and July (81%).
The months with the lowest relative humidity are March and November (74%).

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Average rainfall in December
Onset, MA

Average rainfall in December - Onset, MA
  • Average rainfall in December: 3.58"

The wettest month (with the highest rainfall) is December (3.58").
The driest month (with the least rainfall) is September (1.81").

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Average rainfall days in December
Onset, MA

Average rainfall days in December - Onset, MA
  • Average rainfall days in December: 12.5 days

The month with the highest number of rainy days is July (16 days).
The month with the least rainy days is January (9 days).

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Average snowfall in December
Onset, MA

Average snowfall in December - Onset, MA
  • Average snowfall in December: 1.26"

The months with the highest snowfall are February and March (2.28").
The months with the least snowfall are May, June, July, August and September (0").

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Average snowfall days in December
Onset, MA

Average snowfall days in December - Onset, MA
  • Average snowfall days in December: 3.5 days

The month with the highest number of snowfall days is January (6 days).
The months with the least snowfall days are May, June, July, August and September (0 days).

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Average sea temperature in December
Onset, MA

Average sea temperature in December - Onset, MA
  • Average sea temperature in December: 46.9°F

The best month for swimming (with the highest average sea temperature) is August (68.4°F).
The coldest month (with the lowest average sea temperature) is February (38.2°F).

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

Average daylight in December / Average sunshine in December - Onset, 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 12min).

  • Average sunshine in December: 4h and 5min

The month with the most sunshine is August (Average sunshine: 10h and 42min).
The months with the least sunshine are February and December (Average sunshine: 4h and 48min).

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Average sunshine days in December
Onset, MA

Average sunshine days in December - Onset, MA
  • Average sunshine days in December: 15.6 days

The month with the most sunshine days is November (16.3 days).
The month with the least sunshine days is April (12.5 days).

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Average UV index in December
Onset, MA

Average UV index in December - Onset, MA
  • Average UV index in December: 2

The months with the highest UV index are 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
Onset, MA

Average cloud cover in December - Onset, MA
  • Average cloud cover in December: 48

The month with the most cloud cover is March (Cloud cover 49).
The month with the least cloud cover is August (Cloud cover 28).

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Average visibility in December
Onset, MA

Average visibility in December - Onset, 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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Onset, Massachusetts, USA

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