December weather forecast
Stony Brook, NY

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Weather in December

The first month of the winter, December, is also a frosty month in Stony Brook, New York, with an average temperature ranging between min 36.5°F (2.5°C) and max 43.7°F (6.5°C).

Temperature

December signals a slight drop in average high-temperature, sliding from November's cool 51.8°F (11°C) to a frosty 43.7°F (6.5°C). Nighttime temperature reflects an average dip to a cold 36.5°F (2.5°C) in December, subtly cooler than its daytime highs.

Humidity

In Stony Brook, the average relative humidity in December 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

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

Ocean temperature

In Stony Brook, in December, the average water temperature is 48.9°F (9.4°C).
Note: Swimming in 48.9°F (9.4°C) is deemed hazardous. Exposure to temperatures below 50°F (10°C) leads to immediate severe cold shock and hyperventilation.

Daylight

The month with the shortest days is December, with an average of 9h and 18min of daylight.
On the first day of December, 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

In Stony Brook, 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 in Stony Brook. A UV Index of 2, and less, symbolizes a low health risk from exposure to the Sun's UV rays for the average person.
Note: In December, a daily UV index of 2 turns into the following recommendations:
Babies, children, and individuals with sensitive skin should always have protection against extended sun exposure. The best time to avoid the Sun's harmful UV radiation is during midday when it's most potent. Fend off the sun's harsh rays with appropriate clothing, a wide-brim hat, and UV-protective sunglasses. Be mindful! The reflection from snow can increase the Sun's UV radiation nearly twice.
Updated: Aug 25, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

How cold does it get in December?

The average high-temperature and low-temperature during December are 43.7°F (6.5°C) and 36.5°F (2.5°C) respectively.

What is the average humidity in December?

The average relative humidity in December is 73%.

What is the rainiest month?

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 December?

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

How many days does it snow in December?

In Stony Brook, during December, snow falls for 1.5 days and regularly aggregates up to 1.06" (27mm) of snow.

How cold is the water in December?

In December, the average ocean temperature is 48.9°F (9.4°C). 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.

What is the month with the shortest days?

December has the shortest days of the year, with an average of 9h and 18min of daylight.

How many hours of daylight does Stony Brook have in December?

In December, the average day length is 9h and 17min.

What time are sunrise and sunset in December?

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, sunrise is at 7:17 am and sunset at 4:34 pm EST.

How many hours of sunshine does Stony Brook have in December?

The average sunshine duration in December is 4.8h.

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?

In December, the average daily maximum UV index is 2. A UV Index estimate of 2, and below, represents a minimal hazard to health 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
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).

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).

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).

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%).

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").

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).

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").

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).

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).

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).

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).

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).

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).

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).

Stony Brook, New York, USA

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