December weather forecast
Stony Brook, NY

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Weather in December

December, the first month of the winter in Stony Brook, is still a chilly month, with an average temperature fluctuating between 36.5°F (2.5°C) and 43.7°F (6.5°C).

Temperature

December signifies a minor drop in average high-temperature, transitioning from a fresh 51.8°F (11°C) in November to a chilly 43.7°F (6.5°C). Throughout December nights, Stony Brook records a consistent low-temperature averaging a wintry 36.5°F (2.5°C).

Humidity

In December, the average relative humidity in Stony Brook is 73%.

Rainfall

The month with the most rainfall is December, when the rain falls for 11.4 days and typically aggregates up to 3.58" (91mm) of precipitation.

Snowfall

Months with snowfall are January through March, October through December. In Stony Brook, during December, snow falls for 1.5 days and regularly aggregates up to 1.06" (27mm) of snow. Throughout the year, there are 12.6 snowfall days, and 5.59" (142mm) of snow is accumulated.

Ocean temperature

In Stony Brook, the average seawater temperature in December is 48.9°F (9.4°C).
Note: Swimming at temperatures less than 50°F (10°C) in 48.9°F (9.4°C) is feasible with the right swimsuit; if not, expect cold shock and breathlessness. A quick swim at 55.4°F (13°C) without adequate warmth can be discomforting.

Daylight

With an average of 9h and 18min of daylight, December has the shortest days of the year in Stony Brook.
On the first day of December in Stony Brook, sunrise is at 6:58 am and sunset at 4:25 pm. On the last day of the month, sunrise is at 7:17 am and sunset at 4:34 pm EST.

Sunshine

The average sunshine in December in Stony Brook 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 in Stony Brook. A UV Index estimate of 2, and below, represents a minimal health vulnerability from exposure to the Sun's UV radiation for the average person.
Note: A maximum UV index of 2 in December translates into the following recommendations:
Long-term sun exposure is typically not a concern for most. However, those with sensitive skin, infants, and children must always have protection. The best time to avoid the Sun's harmful UV radiation is during midday when it's most potent. To mitigate harm from sun exposure, pick sunglasses offering UVA and UVB defense. Notice this! Nearly double the intensity of the Sun's UV radiation can be caused by snow reflection.
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Frequently asked questions

How cold does it get in Stony Brook in December?

In Stony Brook, in December, the average high-temperature is 43.7°F (6.5°C), and the average low-temperature is 36.5°F (2.5°C).

What is the average humidity in December in Stony Brook?

In Stony Brook, New York, the average relative humidity in December is 73%.

What is the wettest month in Stony Brook?

December is the month with the most rainfall. Rain falls for 11.4 days and accumulates 3.58" (91mm) of precipitation.

How much does it rain in Stony Brook in December?

In Stony Brook, during December, the rain falls for 11.4 days and regularly aggregates up to 3.58" (91mm) of precipitation.

How much does it snow in Stony Brook in December?

In Stony Brook, in December, during 1.5 snowfall days, 1.06" (27mm) of snow is typically accumulated.

What is the ocean temperature in December in Stony Brook?

In Stony Brook, in December, the average water temperature is 48.9°F (9.4°C). At temperatures below 50°F (10°C), swimming in a suitably protected swimsuit is feasible; otherwise, cold shock and loss of breathing control are imminent. Even a short swim, without thermal protection, at temperatures around 55.4°F (13°C) is not comfortable.

What is the month with the shortest days in Stony Brook?

The month with the shortest days in Stony Brook is December, with an average of 9h and 18min of daylight.

What is the average length of the day in December in Stony Brook?

The average day length in December in Stony Brook, New York, is 9h and 17min.

What time are sunrise and sunset in December in Stony Brook?

In December, on the first day of the month, sunrise is at 6:58 am and sunset at 4:25 pm. On the last day of the month, in Stony Brook, New York, sunrise is at 7:17 am and sunset at 4:34 pm EST.

How long on average sun shines in December in Stony Brook?

In December, the average sunshine duration in Stony Brook, New York, is 4.8h.

What is the month with the lowest UV index in Stony Brook?

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

How high is the UV index in December in Stony Brook?

In Stony Brook, 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
Stony Brook, NY

Average temperature in December - Stony Brook, NY
  • Average high temperature in December: 43.7°F

The warmest month (with the highest average high temperature) is July (79.2°F).
The month with the lowest average high temperature is January (37.6°F).

  • Average low temperature in December: 36.5°F

The months with the highest average low temperature are July and August (71.1°F).
The coldest month (with the lowest average low temperature) is January (29.1°F).

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Average pressure in December
Stony Brook, NY

Average pressure in December - Stony Brook, NY
  • 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).

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Average wind speed in December
Stony Brook, NY

Average wind speed in December - Stony Brook, NY
  • Average wind speed in December: 12.7mph

The windiest month (with the highest average wind speed) is January (12.9mph).
The calmest month (with the lowest average wind speed) is July (8.3mph).

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Average humidity in December
Stony Brook, NY

Average humidity in December - Stony Brook, NY
  • Average humidity in December: 73%

The months with the highest relative humidity are May and June (77%).
The month with the lowest relative humidity is November (71%).

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Average rainfall in December
Stony Brook, NY

Average rainfall in December - Stony Brook, NY
  • 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 January (2.05").

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Average rainfall days in December
Stony Brook, NY

Average rainfall days in December - Stony Brook, NY
  • Average rainfall days in December: 11.4 days

The month with the highest number of rainy days is July (16.5 days).
The month with the least rainy days is January (6.8 days).

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Average snowfall in December
Stony Brook, NY

Average snowfall in December - Stony Brook, NY
  • Average snowfall in December: 1.06"

The month with the highest snowfall is March (2.13").
The months with the least snowfall are April, May, June, July, August and September (0").

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Average snowfall days in December
Stony Brook, NY

Average snowfall days in December - Stony Brook, NY
  • Average snowfall days in December: 1.5 days

The month with the highest number of snowfall days is February (4.4 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
Stony Brook, NY

Average sea temperature in December - Stony Brook, NY
  • Average sea temperature in December: 49°F

The best month for swimming (with the highest average sea temperature) is August (74°F).
The coldest month (with the lowest average sea temperature) is February (39.7°F).

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Average daylight in December /
Average sunshine in December
Stony Brook, NY

Average daylight in December / Average sunshine in December - Stony Brook, NY
  • Average daylight in December: 9h and 2min

The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 18min).

  • Average sunshine in December: 4h and 5min

The month with the most sunshine is July (Average sunshine: 10h and 36min).
The month with the least sunshine is February (Average sunshine: 4h and 42min).

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Average sunshine days in December
Stony Brook, NY

Average sunshine days in December - Stony Brook, NY
  • Average sunshine days in December: 17.6 days

The month with the most sunshine days is November (20.5 days).
The month with the least sunshine days is July (13 days).

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Average UV index in December
Stony Brook, NY

Average UV index in December - Stony Brook, NY
  • 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
Stony Brook, NY

Average cloud cover in December - Stony Brook, NY
  • 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 28).

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Average visibility in December
Stony Brook, NY

Average visibility in December - Stony Brook, NY
  • 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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Stony Brook, New York, USA

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