December weather forecast
Cornwall, CT

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Weather in December

December, the first month of the winter in Cornwall, is still a cold month, with an average temperature fluctuating between 36.7°F (2.6°C) and 25.7°F (-3.5°C).

Temperature

Cornwall in December experiences a subtle temperature decline, with average high-temperatures reducing from a frosty 46.6°F (8.1°C) in November to a wintry 36.7°F (2.6°C). The low-temperature average for Cornwall during December stands at a freezing cold 25.7°F (-3.5°C).

Humidity

The average relative humidity in December is 81%.

Rainfall

In Cornwall, in December, it is raining for 10.9 days, with typically 3.35" (85mm) of accumulated precipitation. Throughout the year, there are 160.5 rainfall days, and 33.86" (860mm) of precipitation is accumulated.

Snowfall

January through May, October through December are months with snowfall. In Cornwall, in December, during 7.1 snowfall days, 3.7" (94mm) of snow is typically accumulated. In Cornwall, during the entire year, snow falls for 40.2 days and aggregates up to 20.39" (518mm) of snow.

Daylight

December has the shortest days of the year, with an average of 9h and 12min of daylight.
On the first day of December, sunrise is at 7:01 am and sunset at 4:23 pm. On the last day of the month, sunrise is at 7:20 am and sunset at 4:32 pm EST.

Sunshine

In Cornwall, Connecticut, the average sunshine in December is 4.5h.

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 threat to health from unsafe exposure to UV radiation for the ordinary person.
Note: In December, the UV index of 2 transforms into the following advice:
Children must always have sun protection, unlike most people, who can tolerate up to an hour in the sun without any burns. Solar radiation is at its peak intensity during midday, so it's advisable to stay indoors or in the shade. Sunglasses that ward off UVA and UVB rays play a pivotal role in reducing solar eye damage. Observe! Snow reflection can nearly intensify the Sun's UV radiation twofold.
Updated: Jun 28, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

How cold is December?

The high-temperature during December is 36.7°F (2.6°C) and the low-temperature is 25.7°F (-3.5°C). In July, the average heat index (a.k.a. 'real feel', 'apparent temperature'), which represents the influence of relative humidity on air temperature, is calculated to be 86°F (30°C).

What is the average humidity in December?

In December, the average relative humidity is 81%.

How much does it rain in December?

In Cornwall, in December, during 10.9 rainfall days, 3.35" (85mm) of precipitation is typically accumulated.

How many days does it snow in December?

In Cornwall, in December, snow falls for 7.1 days, with typically accumulated 3.7" (94mm) of snow.

What is the month with the shortest days in Cornwall?

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

How many hours of daylight does Cornwall have in December?

In Cornwall, the average day length in December is 9h and 12min.

When are sunrise and sunset in December?

In December, on the first day of the month, sunrise is at 7:01 am and sunset at 4:23 pm. On the last day of the month, sunrise is at 7:20 am and sunset at 4:32 pm EST.

How long on average sun shines in December?

In December, the average sunshine duration is 4.5h.

What is the month with 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 intensity in December?

The average daily maximum UV index in December is 2. A UV Index of 2, and less, symbolizes a minimal health vulnerability from unprotected exposure to 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
Cornwall, CT

Average temperature in December - Cornwall, CT
  • Average high temperature in December: 36.7°F

The warmest month (with the highest average high temperature) is July (81.1°F).
The month with the lowest average high temperature is January (30.9°F).

  • Average low temperature in December: 25.7°F

The month with the highest average low temperature is July (61.3°F).
The coldest month (with the lowest average low temperature) is January (18.9°F).

Average pressure in December
Cornwall, CT

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

The month with the highest atmospheric pressure is November (30.09"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).

Average wind speed in December
Cornwall, CT

Average wind speed in December - Cornwall, CT
  • Average wind speed in December: 7.5mph

The windiest months (with the highest average wind speed) are January and March (8mph).
The calmest months (with the lowest average wind speed) are July and August (5mph).

Average humidity in December
Cornwall, CT

Average humidity in December - Cornwall, CT
  • Average humidity in December: 81%

The month with the highest relative humidity is February (82%).
The month with the lowest relative humidity is April (74%).

Average rainfall in December
Cornwall, CT

Average rainfall in December - Cornwall, CT
  • Average rainfall in December: 3.35"

The wettest month (with the highest rainfall) is July (3.54").
The driest month (with the least rainfall) is January (2.17").

Average rainfall days in December
Cornwall, CT

Average rainfall days in December - Cornwall, CT
  • Average rainfall days in December: 10.9 days

The month with the highest number of rainy days is July (17.9 days).
The month with the least rainy days is January (7.7 days).

Average snowfall in December
Cornwall, CT

Average snowfall in December - Cornwall, CT
  • Average snowfall in December: 3.7"

The month with the highest snowfall is February (5.16").
The months with the least snowfall are June, July, August and September (0").

Average snowfall days in December
Cornwall, CT

Average snowfall days in December - Cornwall, CT
  • Average snowfall days in December: 7.1 days

The month with the highest number of snowfall days is February (10.3 days).
The months with the least snowfall days are June, July, August and September (0 days).

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

Average daylight in December / Average sunshine in December - Cornwall, CT
  • 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 3min

The month with the most sunshine is July (Average sunshine: 10h and 6min).
The month with the least sunshine is February (Average sunshine: 4h and 12min).

Average sunshine days in December
Cornwall, CT

Average sunshine days in December - Cornwall, CT
  • Average sunshine days in December: 14.8 days

The month with the most sunshine days is January (16.8 days).
The month with the least sunshine days is June (10.8 days).

Average UV index in December
Cornwall, CT

Average UV index in December - Cornwall, CT
  • Average UV index in December: 2

The month with the highest UV index is June (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
Cornwall, CT

Average cloud cover in December - Cornwall, CT
  • Average cloud cover in December: 52

The month with the most cloud cover is February (Cloud cover 53).
The months with the least cloud cover are July and August (Cloud cover 37).

Average visibility in December
Cornwall, CT

Average visibility in December - Cornwall, CT
  • Average visibility in December: 5mi

The months with the highest visibility are April and November (6mi).
The months with the lowest visibility are January, February, March, May, June, July, August, September, October and December (5mi).

Cornwall, Connecticut, USA

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