December weather forecast
Greenwich, CT

The straight road of North Street cutting through the green leafy suburbs of the scenic Greenwich City in Connecticut
The straight road of North Street cutting through the green leafy suburbs of the scenic Greenwich City in Connecticut

Weather in December

The first month of the winter, December, is still a cold month in Greenwich, Connecticut, with an average temperature fluctuating between 33.3°F (0.7°C) and 41.9°F (5.5°C).

Temperature

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

Humidity

The months with the highest humidity are February, May and December, with an average relative humidity of 75%.

Rainfall

In December, in Greenwich, the rain falls for 12 days. Throughout December, 3.86" (98mm) of precipitation is accumulated. Throughout the year, in Greenwich, Connecticut, there are 165.6 rainfall days, and 37.64" (956mm) of precipitation is accumulated.

Snowfall

January through April, November and December are months with snowfall. In Greenwich, during December, snow falls for 4.6 days and regularly aggregates up to 1.61" (41mm) of snow. Throughout the year, there are 25.5 snowfall days, and 8.78" (223mm) of snow is accumulated.

Ocean temperature

In December, the average ocean temperature in Greenwich is 47.1°F (8.4°C).
Note: Swimming in 47.1°F (8.4°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

December has the shortest days of the year, with an average of 9h and 17min of daylight.
On the first day of the month, sunrise is at 7:00 am and sunset at 4:27 pm. On the last day of December, in Greenwich, sunrise is at 7:19 am and sunset at 4:35 pm EST.

Sunshine

In Greenwich, Connecticut, the average sunshine in December is 4.8h.

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 low health risk from unsafe exposure to UV radiation for ordinary individuals.
Note: The average daily UV index of 2 in December transform into the following instructions:
People with sensitive skin, children, and babies should always be protected from prolonged sun exposure. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. A wide-brim hat offers excellent sun protection for the eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.
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FAQ

What are the most humid months in Greenwich?

February, May and December, with an average relative humidity of 75%, are most humid months in Greenwich.

What is the average humidity in December in Greenwich?

In Greenwich, the average relative humidity in December is 75%.

How many days does it rain in December in Greenwich?

In Greenwich, during December, the rain falls for 12 days and regularly aggregates up to 3.86" (98mm) of precipitation.

How many days does it snow in December in Greenwich?

In Greenwich, Connecticut, in December, snow falls for 4.6 days, with typically accumulated 1.61" (41mm) of snow.

How cold is the water in December in Greenwich?

In Greenwich, in December, the average water temperature is 47.1°F (8.4°C). Swimming in 47.1°F (8.4°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 Greenwich?

With an average of 9h and 17min of daylight, December has the shortest days of the year in Greenwich, Connecticut.

How many hours of daylight does Greenwich have in December?

The average day length in December is 9h and 17min.

When is the sunrise / sunset in December in Greenwich?

In December, on the first day of the month, sunrise is at 7:00 am and sunset at 4:27 pm. On the last day of the month, in Greenwich, sunrise is at 7:19 am and sunset at 4:35 pm EST.

How many hours of sunshine does Greenwich have in December?

The average sunshine duration in December is 4.8h.

What are the months with the lowest UV index in Greenwich?

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

How high is the UV index in December in Greenwich?

In December, the average daily maximum UV index in Greenwich, Connecticut, is 2. A UV Index estimate of 2, and below, represents a minimal health vulnerability 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
Greenwich, CT

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

The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (35.8°F).

  • Average low temperature in December: 33.3°F

The month with the highest average low temperature is July (69.1°F).
The coldest month (with the lowest average low temperature) is January (26.1°F).

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Average pressure in December
Greenwich, CT

Average pressure in December - Greenwich, CT
  • Average pressure in December: 30.06"Hg

The month with the highest atmospheric pressure is November (30.1"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).

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Average wind speed in December
Greenwich, CT

Average wind speed in December - Greenwich, CT
  • Average wind speed in December: 9.6mph

The windiest month (with the highest average wind speed) is January (9.9mph).
The calmest month (with the lowest average wind speed) is July (6.5mph).

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Average humidity in December
Greenwich, CT

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

The months with the highest relative humidity are February, May and December (75%).
The month with the lowest relative humidity is August (71%).

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Average rainfall in December
Greenwich, CT

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

The wettest month (with the highest rainfall) is July (4.13").
The driest months (with the least rainfall) are January and February (2.4").

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Average rainfall days in December
Greenwich, CT

Average rainfall days in December - Greenwich, CT
  • Average rainfall days in December: 12 days

The month with the highest number of rainy days is July (18.1 days).
The month with the least rainy days is January (7.9 days).

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Average snowfall in December
Greenwich, CT

Average snowfall in December - Greenwich, CT
  • Average snowfall in December: 1.61"

The month with the highest snowfall is February (2.52").
The months with the least snowfall are May, June, July, August, September and October (0").

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Average snowfall days in December
Greenwich, CT

Average snowfall days in December - Greenwich, CT
  • Average snowfall days in December: 4.6 days

The month with the highest number of snowfall days is January (7.2 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
Greenwich, CT

Average sea temperature in December - Greenwich, CT
  • Average sea temperature in December: 47.1°F

The best month for swimming (with the highest average sea temperature) is August (73.1°F).
The coldest month (with the lowest average sea temperature) is February (39.5°F).

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

Average daylight in December / Average sunshine in December - Greenwich, CT
  • Average daylight in December: 9h and 17min

The month with the longest days is June (Average daylight: 15h and 5min).
The month with the shortest days is December (Average daylight: 9h and 17min).

  • Average sunshine in December: 4h and 48min

The month with the most sunshine is July (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
Greenwich, CT

Average sunshine days in December - Greenwich, CT
  • Average sunshine days in December: 15.2 days

The month with the most sunshine days is November (17.8 days).
The month with the least sunshine days is June (10.7 days).

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Average UV index in December
Greenwich, CT

Average UV index in December - Greenwich, 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
Greenwich, CT

Average cloud cover in December - Greenwich, CT
  • Average cloud cover in December: 49

The month with the most cloud cover is December (Cloud cover 49).
The month with the least cloud cover is August (Cloud cover 31).

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Average visibility in December
Greenwich, CT

Average visibility in December - Greenwich, 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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