December weather forecast
Mendham, NJ

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Weather in December

December, the first month of the winter in Mendham, is also an icy month, with an average temperature fluctuating between 29.3°F (-1.5°C) and 41°F (5°C).

Temperature

In December, the average high-temperature goes from a cool 50.4°F (10.2°C) in November to a wintry 41°F (5°C). During the month of December, an average temperature of 29.3°F (-1.5°C) is noted during the nights in Mendham.

Humidity

The average relative humidity in December is 79%.

Rainfall

The month with the most rainfall is December, when the rain falls for 10.9 days and typically aggregates up to 3.39" (86mm) of precipitation.

Snowfall

Months with snowfall are January through May, October through December. In Mendham, in December, snow falls for 4 days, with typically accumulated 2.13" (54mm) of snow. Throughout the year, there are 28.5 snowfall days, and 14.49" (368mm) of snow is accumulated.

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 7:03 am and sunset at 4:31 pm. On the last day of December, sunrise is at 7:22 am and sunset at 4:40 pm EST.

Sunshine

In Mendham, the average sunshine in December is 4.8h.

UV index

The months with the lowest UV index are January through March, November and December, with an average maximum UV index of 2. A UV Index estimate of 2, and below, represents a minimal health hazard from exposure to the Sun's UV radiation for the average person.
Note: A daily high UV index of 2 in December leads to these guidelines:
While most individuals can withstand prolonged sun exposure, it is imperative that babies, children, and those with sensitive skin always be shielded. The best time to avoid the Sun's harmful UV radiation is during midday when it's most potent. Sunglasses that guard against UVA and UVB rays are pivotal in minimizing sun-induced ocular damage. Take careful note! The UV radiation of the Sun can be nearly doubled by snow reflection.
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Frequently asked questions

How cold is December in Mendham?

In December, in Mendham, the average high-temperature is 41°F (5°C), and the average low-temperature is 29.3°F (-1.5°C). The average heat index (a.k.a. 'felt air temperature', 'real feel'), which combines air temperature and relative humidity, in August is estimated at 86°F (30°C).

What is the average humidity in December in Mendham?

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

What is the rainiest month in Mendham?

December is the month with the most rainfall in Mendham. Rain falls for 10.9 days and accumulates 3.39" (86mm) of precipitation.

How many days does it rain in December in Mendham?

In Mendham, in December, it is raining for 10.9 days, with typically 3.39" (86mm) of accumulated precipitation.

How much does it snow in Mendham in December?

In Mendham, in December, during 4 snowfall days, 2.13" (54mm) of snow is typically accumulated.

What is the month with the shortest days in Mendham?

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

How many hours of daylight does Mendham have in December?

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

When are sunrise and sunset in December in Mendham?

On the first day of December in Mendham, sunrise is at 7:03 am and sunset at 4:31 pm. On the last day of the month, sunrise is at 7:22 am and sunset at 4:40 pm EST.

How many hours of sunshine does Mendham have in December?

The average sunshine duration in December is 4.8h.

What is the month with the lowest UV index in Mendham?

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

What is the UV index reading in December in Mendham?

In December, the average daily maximum UV index is 2. A UV Index reading of 2, and below, represents a low health threat 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
Mendham, NJ

Average temperature in December - Mendham, NJ
  • Average high temperature in December: 41°F

The warmest month (with the highest average high temperature) is July (83.7°F).
The month with the lowest average high temperature is January (35.1°F).

  • Average low temperature in December: 29.3°F

The month with the highest average low temperature is July (64.8°F).
The coldest month (with the lowest average low temperature) is January (22.3°F).

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Average pressure in December
Mendham, NJ

Average pressure in December - Mendham, NJ
  • Average pressure in December: 30.08"Hg

The month with the highest atmospheric pressure is November (30.11"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).

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Average wind speed in December
Mendham, NJ

Average wind speed in December - Mendham, NJ
  • Average wind speed in December: 7.5mph

The windiest month (with the highest average wind speed) is March (8.3mph).
The calmest month (with the lowest average wind speed) is August (5.1mph).

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Average humidity in December
Mendham, NJ

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

The months with the highest relative humidity are February and October (80%).
The month with the lowest relative humidity is April (75%).

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Average rainfall in December
Mendham, NJ

Average rainfall in December - Mendham, NJ
  • Average rainfall in December: 3.39"

The wettest month (with the highest rainfall) is December (3.39").
The driest month (with the least rainfall) is September (1.85").

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Average rainfall days in December
Mendham, NJ

Average rainfall days in December - Mendham, NJ
  • Average rainfall days in December: 10.9 days

The months with the highest number of rainy days are May and July (17.3 days).
The month with the least rainy days is January (8.9 days).

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Average snowfall in December
Mendham, NJ

Average snowfall in December - Mendham, NJ
  • Average snowfall in December: 2.13"

The month with the highest snowfall is March (4.49").
The months with the least snowfall are June, July, August and September (0").

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Average snowfall days in December
Mendham, NJ

Average snowfall days in December - Mendham, NJ
  • Average snowfall days in December: 4 days

The month with the highest number of snowfall days is January (8.3 days).
The months with the least snowfall days are June, July, August and September (0 days).

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

Average daylight in December / Average sunshine in December - Mendham, 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 30min).
The month with the least sunshine is February (Average sunshine: 4h and 36min).

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Average sunshine days in December
Mendham, NJ

Average sunshine days in December - Mendham, NJ
  • Average sunshine days in December: 16.6 days

The month with the most sunshine days is November (17.6 days).
The month with the least sunshine days is May (11.4 days).

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Average UV index in December
Mendham, NJ

Average UV index in December - Mendham, NJ
  • Average UV index in December: 2

The months with the highest UV index are June and July (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
Mendham, NJ

Average cloud cover in December - Mendham, NJ
  • Average cloud cover in December: 49

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

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Average visibility in December
Mendham, NJ

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

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

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Mendham, New Jersey, USA

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