December weather forecast
Mahwah, NJ

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Weather in December

As Mahwah steps into December, it gets enveloped in the encompassing cold of the winter season. With falling temperatures comes an increased likelihood of snowfall with an approximate accumulation of 1.81" (46mm) across 5.1 days. Clear, cold, and crisp days define Mahwah's mid-winter weather, wrapping up the year on a frosty yet beautiful note.

Temperature

Mahwah's December weather features a mild decline in high-temperatures, reducing from a cool 50°F (10°C) in November to a wintry 40.1°F (4.5°C). Mahwah records an average nighttime low-temperature of 29.1°F (-1.6°C) throughout December.

Humidity

The months with the highest humidity are February and December, with an average relative humidity of 79%.

Rainfall

The month with the most rainfall is December, when the rain falls for 10.8 days and typically aggregates up to 2.68" (68mm) of precipitation.

Snowfall

Months with snowfall in Mahwah are January through May, October through December. In Mahwah, in December, during 5.1 snowfall days, 1.81" (46mm) of snow is typically accumulated. In Mahwah, during the entire year, snow falls for 28.5 days and aggregates up to 10.98" (279mm) of snow.

Daylight

The month with the shortest days is December, with an average of 9h and 18min of daylight.
On the first day of the month, sunrise is at 7:02 am and sunset at 4:28 pm. On the last day of December, in Mahwah, sunrise is at 7:21 am and sunset at 4:38 pm EST.

Sunshine

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. A UV Index value of 2, and less, symbolizes a low health risk from unprotected exposure to Sun's UV rays for the ordinary person.
Note: The maximum daily UV index of 2 in December converts 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. To prevent harmful UV exposure, minimize direct contact with the Sun around midday. It's wise to wear UVA and UVB-blocking sunglasses when the sun shines brightly. Remember this! The UV radiation of the Sun can be nearly doubled by the reflective properties of snow.
Updated: Jun 19, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

Is December cold?

During December, Mahwah experiences an average high-temperature of 40.1°F (4.5°C) and a low-temperature of 29.1°F (-1.6°C). The average heat index (a.k.a. 'apparent temperature', 'real feel'), which combines relative humidity and air temperature, in August is calculated to be 87.8°F (31°C).

What is the most humid month?

February and December, with an average relative humidity of 79%, are most humid months.

What is the average humidity in December?

In Mahwah, the average relative humidity in December is 79%.

What is the wettest month?

The month with the most rainfall in Mahwah is December, when the rain falls for 10.8 days and typically aggregates up to 2.68" (68mm) of precipitation.

How many days does it rain in December?

In Mahwah, during December, the rain falls for 10.8 days and regularly aggregates up to 2.68" (68mm) of precipitation.

How many days does it snow in December?

In Mahwah, in December, during 5.1 snowfall days, 1.81" (46mm) of snow is typically accumulated.

What is the month with the shortest days?

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

What time are sunrise and sunset in December?

In December, on the first day of the month, sunrise is at 7:02 am and sunset at 4:28 pm. On the last day of the month, sunrise is at 7:21 am and sunset at 4:38 pm EST.

How many hours of sunshine does Mahwah have in December?

In December, the average sunshine duration is 4.8h.

What are the months 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.

How high is the UV index in December?

In December, the average daily maximum UV index is 2. A UV Index estimate of 2, and below, represents a low health risk from 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
Mahwah, NJ

Average temperature in December - Mahwah, NJ
  • Average high temperature in December: 40.1°F

The warmest month (with the highest average high temperature) is July (84.2°F).
The month with the lowest average high temperature is January (34.3°F).

  • Average low temperature in December: 29.1°F

The month with the highest average low temperature is July (65.3°F).
The coldest month (with the lowest average low temperature) is January (21.7°F).

Average pressure in December
Mahwah, NJ

Average pressure in December - Mahwah, NJ
  • 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
Mahwah, NJ

Average wind speed in December - Mahwah, NJ
  • Average wind speed in December: 7.1mph

The windiest month (with the highest average wind speed) is March (7.7mph).
The calmest month (with the lowest average wind speed) is August (5mph).

Average humidity in December
Mahwah, NJ

Average humidity in December - Mahwah, NJ
  • Average humidity in December: 79%

The months with the highest relative humidity are February and December (79%).
The month with the lowest relative humidity is April (72%).

Average rainfall in December
Mahwah, NJ

Average rainfall in December - Mahwah, NJ
  • Average rainfall in December: 2.68"

The wettest month (with the highest rainfall) is December (2.68").
The driest month (with the least rainfall) is September (1.34").

Average rainfall days in December
Mahwah, NJ

Average rainfall days in December - Mahwah, NJ
  • Average rainfall days in December: 10.8 days

The month with the highest number of rainy days is July (16.6 days).
The month with the least rainy days is January (7.8 days).

Average snowfall in December
Mahwah, NJ

Average snowfall in December - Mahwah, NJ
  • Average snowfall in December: 1.81"

The month with the highest snowfall is February (2.91").
The months with the least snowfall are June, July, August and September (0").

Average snowfall days in December
Mahwah, NJ

Average snowfall days in December - Mahwah, NJ
  • Average snowfall days in December: 5.1 days

The month with the highest number of snowfall days is February (7.7 days).
The months with the least snowfall days are June, July, August and September (0 days).

Average daylight in December /
Average sunshine in December
Mahwah, NJ

Average daylight in December / Average sunshine in December - Mahwah, NJ
  • 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 24min).
The month with the least sunshine is February (Average sunshine: 4h and 30min).

Average sunshine days in December
Mahwah, NJ

Average sunshine days in December - Mahwah, NJ
  • Average sunshine days in December: 15.7 days

The month with the most sunshine days is November (18.8 days).
The month with the least sunshine days is June (11.8 days).

Average UV index in December
Mahwah, NJ

Average UV index in December - Mahwah, NJ
  • 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
Mahwah, NJ

Average cloud cover in December - Mahwah, NJ
  • Average cloud cover in December: 48

The months with the most cloud cover are February and March (Cloud cover 49).
The month with the least cloud cover is August (Cloud cover 33).

Average visibility in December
Mahwah, NJ

Average visibility in December - Mahwah, NJ
  • Average visibility in December: 6mi

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

Mahwah, New Jersey, USA

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