December weather forecast
Roslyn Harbor, NY

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Weather in December

December, the first month of the winter in Roslyn Harbor, is still a cold month, with an average temperature varying between 34.7°F (1.5°C) and 42.4°F (5.8°C).

Temperature

The start of December signals a gentle decrease in the average high-temperature, transitioning from a cool 51.1°F (10.6°C) in November to an icy 42.4°F (5.8°C). Roslyn Harbor observes a slightly reduced average nighttime temperature of 34.7°F (1.5°C) during December.

Humidity

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

Rainfall

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

Snowfall

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

Ocean temperature

In Roslyn Harbor, New York, in December, the average water temperature is 48°F (8.9°C).
Note: It is life-risking to swim in 48°F (8.9°C). Briefly staying in 55.4°F (13°C) waters feels unsettling, and temperatures below 50°F (10°C) might result in cold shock and loss of breath control, hinging on personal endurance.

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 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 4:36 pm EST.

Sunshine

In Roslyn Harbor, New York, the average sunshine in December is 4.9h.

UV index

The months with the lowest UV index in Roslyn Harbor are January through March, November and December, with an average maximum UV index of 2. A UV Index reading of 2, and below, represents a minimal health hazard from unsafe exposure to UV radiation for the average person.
Note: In December, a daily maximum UV index of 2 leads to the following instructions:
For the majority, extended sun exposure is not of great concern. Infants and people with sensitive skin must always be protected. UV radiation from the Sun is most dangerous during midday; take precautions and seek shade. During bright days, sunglasses that offer UVA and UVB defense are recommended. Consider carefully! The reflective quality of snow can almost double the intensity of the Sun's UV radiation.
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Frequently asked questions

How cold is December in Roslyn Harbor?

In December, in Roslyn Harbor, the average high-temperature is 42.4°F (5.8°C), and the average low-temperature is 34.7°F (1.5°C). The average heat index (a.k.a. 'feels like', 'real feel'), which factors the actual air temperature with the relative humidity, in July is estimated at 86°F (30°C).

What are the most humid months in Roslyn Harbor?

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

What is the average humidity in December in Roslyn Harbor?

In Roslyn Harbor, New York, the average relative humidity in December is 75%.

What is the wettest month in Roslyn Harbor?

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

How many days does it rain in December in Roslyn Harbor?

In Roslyn Harbor, in December, during 12.9 rainfall days, 4.06" (103mm) of precipitation is typically accumulated.

How many days does it snow in December in Roslyn Harbor?

In Roslyn Harbor, New York, during December, snow falls for 3.5 days and regularly aggregates up to 1.54" (39mm) of snow.

What is the ocean temperature in December in Roslyn Harbor?

In December, the average ocean temperature is 48°F (8.9°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 Roslyn Harbor?

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

What is the average length of the day in December in Roslyn Harbor?

The average day length in December in Roslyn Harbor is 9h and 18min.

When are sunrise and sunset in December in Roslyn Harbor?

On the first day of December in Roslyn Harbor, 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 4:36 pm EST.

How long on average sun shines in December in Roslyn Harbor?

The average sunshine duration in December in Roslyn Harbor is 4.9h.

What are the months with the lowest UV index in Roslyn Harbor?

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

What is the UV index reading in December in Roslyn Harbor?

The average daily maximum UV index in December in Roslyn Harbor, New York, is 2. A UV Index of 2, and less, symbolizes a low health risk 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
Roslyn Harbor, NY

Average temperature in December - Roslyn Harbor, 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).

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Average pressure in December
Roslyn Harbor, NY

Average pressure in December - Roslyn Harbor, 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).

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Average wind speed in December
Roslyn Harbor, NY

Average wind speed in December - Roslyn Harbor, 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).

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Average humidity in December
Roslyn Harbor, NY

Average humidity in December - Roslyn Harbor, 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%).

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Average rainfall in December
Roslyn Harbor, NY

Average rainfall in December - Roslyn Harbor, 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").

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Average rainfall days in December
Roslyn Harbor, NY

Average rainfall days in December - Roslyn Harbor, 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).

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Average snowfall in December
Roslyn Harbor, NY

Average snowfall in December - Roslyn Harbor, 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").

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Average snowfall days in December
Roslyn Harbor, NY

Average snowfall days in December - Roslyn Harbor, 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).

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Average sea temperature in December
Roslyn Harbor, NY

Average sea temperature in December - Roslyn Harbor, 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).

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

Average daylight in December / Average sunshine in December - Roslyn Harbor, 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 42min).
The month with the least sunshine is February (Average sunshine: 4h and 48min).

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Average sunshine days in December
Roslyn Harbor, NY

Average sunshine days in December - Roslyn Harbor, 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).

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Average UV index in December
Roslyn Harbor, NY

Average UV index in December - Roslyn Harbor, 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
Roslyn Harbor, NY

Average cloud cover in December - Roslyn Harbor, 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).

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Average visibility in December
Roslyn Harbor, NY

Average visibility in December - Roslyn Harbor, 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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Roslyn Harbor, New York, USA

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