December weather forecast
Groton, CT

Weather in December

December, the first month of the winter in Groton, is also a wintry month, with an average temperature fluctuating between 33.3°F (0.7°C) and 41.9°F (5.5°C).

Temperature

In December, the average high-temperature decreases from a fresh 50.9°F (10.5°C) in November to a wintry 41.9°F (5.5°C). The average low-temperature, in Groton, is 33.3°F (0.7°C).

Humidity

In December, the average relative humidity is 75%.

Rainfall

The month with the most rainfall in Groton is December, when the rain falls for 13.4 days and typically aggregates up to 3.86" (98mm) of precipitation.

Snowfall

January through April, November and December are months with snowfall. In December, it is snowing for 4.8 days. Throughout December, 1.22" (31mm) of snow is accumulated. In Groton, during the entire year, snow falls for 24 days and aggregates up to 7.68" (195mm) of snow.

Ocean temperature

In Groton, the average water temperature is 48.9°F (9.4°C).
Note: Swimming in 48.9°F (9.4°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.

Daylight

The month with the shortest days in Groton is December, with an average of 9h and 15min of daylight.
On the first day of December in Groton, sunrise is at 6:54 am and sunset at 4:19 pm. On the last day of the month, sunrise is at 7:14 am and sunset at 4:28 pm EST.

Sunshine

The months with the least sunshine in Groton are February and December, with an average of 4.9h 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 value of 2, and less, symbolizes a minimal health hazard from unsafe exposure to UV radiation for the average person.
Note: The average daily UV index of 2 in December transform into the following instructions:
For the majority, extended sun exposure is not of great concern. Infants and people with sensitive skin must always be protected. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.
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FAQ

What is the average humidity in December in Groton?

The average relative humidity in December in Groton, Connecticut, is 75%.

What is the wettest month in Groton?

The month with the most rainfall in Groton, Connecticut, is December, when the rain falls for 13.4 days and typically aggregates up to 3.86" (98mm) of precipitation.

How much does it rain in Groton in December?

In Groton, Connecticut, during December, the rain falls for 13.4 days and regularly aggregates up to 3.86" (98mm) of precipitation.

How much does it snow in Groton in December?

In December, in Groton, it is snowing for 4.8 days. Throughout December, 1.22" (31mm) of snow is accumulated.

How cold is the water in December in Groton?

In Groton, in December, the average water temperature is 48.9°F (9.4°C). Swimming in 48.9°F (9.4°C) is considered dangerous. Unprotected immersion in temperatures below 50°F (10°C) causes quickly maximum intensity cold shock with hyperventilation.

What is the month with the shortest days in Groton?

The month with the shortest days is December, with an average of 9h and 15min of daylight.

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

In December, the average day length in Groton, Connecticut, is 9h and 15min.

When are sunrise and sunset in December in Groton?

On the first day of December in Groton, sunrise is at 6:54 am and sunset at 4:19 pm. On the last day of the month, sunrise is at 7:14 am and sunset at 4:28 pm EST.

What is the month with the least sunshine in Groton?

February and December, with an average of 4.9h of sunshine, are months with the least sunshine in Groton, Connecticut.

How long on average sun shines in December in Groton?

In December, the average sunshine duration is 4.9h.

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

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

How high is the UV index in December in Groton?

The average daily maximum UV index in December in Groton, Connecticut, is 2. A UV Index value of 2, and less, symbolizes a low health risk from unsafe exposure to Sun's UV rays.
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
Groton, CT

Average temperature in December - Groton, CT
  • Average high temperature in December: 41.9°F

The warmest month (with the highest average high temperature) is July (78.6°F).
The month with the lowest average high temperature is January (36.1°F).

  • Average low temperature in December: 33.3°F

The month with the highest average low temperature is July (66.7°F).
The coldest month (with the lowest average low temperature) is January (26.2°F).

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Average pressure in December
Groton, CT

Average pressure in December - Groton, CT
  • Average pressure in December: 30.05"Hg

The month with the highest atmospheric pressure is November (30.08"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).

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Average wind speed in December
Groton, CT

Average wind speed in December - Groton, CT
  • Average wind speed in December: 11.5mph

The windiest month (with the highest average wind speed) is January (11.9mph).
The calmest months (with the lowest average wind speed) are July and August (7.8mph).

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Average humidity in December
Groton, CT

Average humidity in December - Groton, CT
  • Average humidity in December: 75%

The month with the highest relative humidity is June (80%).
The months with the lowest relative humidity are January, March, April and November (74%).

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Average rainfall in December
Groton, CT

Average rainfall in December - Groton, CT
  • Average rainfall in December: 3.86"

The wettest month (with the highest rainfall) is December (3.86").
The driest month (with the least rainfall) is September (1.65").

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Average rainfall days in December
Groton, CT

Average rainfall days in December - Groton, CT
  • Average rainfall days in December: 13.4 days

The month with the highest number of rainy days is July (15.8 days).
The month with the least rainy days is February (9.5 days).

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Average snowfall in December
Groton, CT

Average snowfall in December - Groton, CT
  • Average snowfall in December: 1.22"

The month with the highest snowfall is March (2.56").
The months with the least snowfall are May, June, July, August, September and October (0").

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Average snowfall days in December
Groton, CT

Average snowfall days in December - Groton, CT
  • Average snowfall days in December: 4.8 days

The month with the highest number of snowfall days is February (6.8 days).
The months with the least snowfall days are June, July, August, September and October (0 days).

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Average sea temperature in December
Groton, CT

Average sea temperature in December - Groton, CT
  • Average sea temperature in December: 48.9°F

The best month for swimming (with the highest average sea temperature) is August (72.1°F).
The coldest month (with the lowest average sea temperature) is February (38.8°F).

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Average daylight in December /
Average sunshine in December
Groton, CT

Average daylight in December / Average sunshine in December - Groton, CT
  • Average daylight in December: 9h and 15min

The month with the longest days is June (Average daylight: 15h and 7min).
The month with the shortest days is December (Average daylight: 9h and 15min).

  • Average sunshine in December: 4h and 54min

The month with the most sunshine is August (Average sunshine: 10h and 36min).
The months with the least sunshine are February and December (Average sunshine: 4h and 54min).

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Average sunshine days in December
Groton, CT

Average sunshine days in December - Groton, CT
  • Average sunshine days in December: 13.9 days

The month with the most sunshine days is November (16.5 days).
The month with the least sunshine days is February (12.5 days).

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Average UV index in December
Groton, CT

Average UV index in December - Groton, CT
  • 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
Groton, CT

Average cloud cover in December - Groton, CT
  • Average cloud cover in December: 47

The months with the most cloud cover are February, March and December (Cloud cover 47).
The month with the least cloud cover is August (Cloud cover 29).

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Average visibility in December
Groton, CT

Average visibility in December - Groton, CT
  • 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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