December weather forecastRoslyn, NY

December

Weather in December

December, the first month of the winter in Roslyn, is also a wintry month, with an average temperature ranging between min 34.7°F (1.5°C) and max 42.4°F (5.8°C).

Temperature

Roslyn's December weather shows a modest shift in high-temperatures, falling from November's cool 51.1°F (10.6°C) to an icy 42.4°F (5.8°C). Roslyn's December nights witness minimal differential from the daytime temperatures, with averages of 34.7°F (1.5°C).

Humidity

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

Rainfall

December is the month with the most rainfall in Roslyn. Rain falls for 12.9 days and accumulates 4.06" (103mm) of precipitation.

Snowfall

January through April, November and December are months with snowfall. In Roslyn, New York, in December, during 3.5 snowfall days, 1.54" (39mm) of snow is typically accumulated. In Roslyn, during the entire year, snow falls for 22.2 days and aggregates up to 7.24" (184mm) of snow.

Ocean temperature

In Roslyn, New York, the average seawater temperature in December is 48°F (8.9°C).
Note: If planning to swim in 48°F (8.9°C) under 50°F (10°C), wear a protective suit. Neglecting this advice might cause immediate cold shock and troubled breathing. A splash around 55.4°F (13°C) is not much warmer.

Daylight

December has the shortest days of the year, with an average of 9h and 18min 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, sunrise is at 7:18 am and sunset at 4:37 pm EST.

Sunshine

The average sunshine in December is 4.9h.

UV index

January through March, November and December, with an average maximum UV index of 2, are months with the lowest UV index in Roslyn. A UV Index of 2, and less, symbolizes a low health risk from unprotected exposure to Sun's UV rays for ordinary individuals.
Note: The UV index of 2 in December translates into these instructions:
Most individuals face no significant issues with extended sun exposure, but it is always essential to protect children, babies, and those with sensitive skin. Avoiding direct sun during mid-day hours can prevent harmful UV radiation exposure. Safeguard your eyes, ears, and face from sun rays with the aid of a wide-brim hat. Beware! Reflection from snow can magnify the Sun's UV radiation nearly twofold.

Updated: Aug 4, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

In December, the average high-temperature and low-temperature are 42.4°F (5.8°C) and 34.7°F (1.5°C) respectively. The average heat index (a.k.a. 'real feel', 'felt air temperature'), which combines air temperature and relative humidity, in July is evaluated at 86°F (30°C).

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

The average relative humidity in December is 75%.

The month with the most rainfall is December, when the rain falls for 12.9 days and typically aggregates up to 4.06" (103mm) of precipitation.

In Roslyn, in December, it is raining for 12.9 days, with typically 4.06" (103mm) of accumulated precipitation.

In December, it is snowing for 3.5 days. Throughout December, 1.54" (39mm) of snow is accumulated.

In Roslyn, New York, in December, the average water temperature is 48°F (8.9°C). Swimming in 48°F (8.9°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.

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

In Roslyn, the average day length in December is 9h and 19min.

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, sunrise is at 7:18 am and sunset at 4:37 pm EST.

The average sunshine duration in December is 4.9h.

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

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

Today

Tomorrow

Long-term

Year J F M A M J J A S O N December

Nov

December

Jan

Average high temperature

51.1°F

42.4°F

36.5°F

Average low temperature

Average pressure

Average wind speed

Average max. wind speed

11.2mph

11.6mph

11.9mph

Average wind speed gusts

Average humidity

Average rainfall

Average rainfall days

Average snowfall

Average snowfall days

0.8

3.5

6.8

Average sea temperature

Average daylight

Average sunshine

Average sunshine days

15.5

17.3

Average UV index

Average cloud cover

Average visibility

Average temperature in December
Roslyn, NY

Average high temperature in December: 42.4°F

The warmest month (with the highest average high temperature) is July (81.5°F).
The month with the lowest average high temperature is January (36.5°F).

Average low temperature in December: 34.7°F

The months with the highest average low temperature are July and August (70.3°F).
The coldest month (with the lowest average low temperature) is January (27.3°F).

Average pressure in December
Roslyn, NY

Average pressure in December: 30.07"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).

Average wind speed in December
Roslyn, NY

Average wind speed in December: 10.8mph

The windiest month (with the highest average wind speed) is January (11.2mph).
The calmest month (with the lowest average wind speed) is July (7.3mph).

Average humidity in December
Roslyn, NY

Average humidity in December: 75%

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

Average rainfall in December
Roslyn, NY

Average rainfall in December: 4.06"

The wettest month (with the highest rainfall) is December (4.06").
The driest month (with the least rainfall) is September (2.4").

Average rainfall days in December
Roslyn, NY

Average rainfall days in December: 12.9 days

The month with the highest number of rainy days is July (17.9 days).
The month with the least rainy days is January (9.3 days).

Average snowfall in December
Roslyn, NY

Average snowfall in December: 1.54"

The month with the highest snowfall is March (2.01").
The months with the least snowfall are May, June, July, August, September and October (0").

Average snowfall days in December
Roslyn, NY

Average snowfall days in December: 3.5 days

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

Average sea temperature in December
Roslyn, NY

Average sea temperature in December: 48.1°F

The best month for swimming (with the highest average sea temperature) is August (74.1°F).
The coldest month (with the lowest average sea temperature) is February (39.9°F).

Average daylight in December /
Average sunshine in December
Roslyn, NY

Average daylight in December: 9h and 18min

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 54min

The month with the most sunshine is July (Average sunshine: 10h and 42min).
The month with the least sunshine is February (Average sunshine: 4h and 48min).

Average sunshine days in December
Roslyn, NY

Average sunshine days in December: 15.5 days

The month with the most sunshine days is November (18 days).
The month with the least sunshine days is July (10.6 days).

Average UV index in December
Roslyn, 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
Roslyn, NY

Average cloud cover in December: 47

The months with the most cloud cover are February and December (Cloud cover 47).
The months with the least cloud cover are July and August (Cloud cover 29).

Average visibility in December
Roslyn, 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).