December weather forecast and climate
Summit, NJ

The first month of the winter, December, is also a wintry month in Summit, New Jersey, with average temperature ranging between min 29.7°F (-1.3°C) and max 40.8°F (4.9°C).

Temperature

In December, the average high-temperature drops, from a cool 50.5°F (10.3°C) in November, to a wintry 40.8°F (4.9°C). In Summit, New Jersey, in December, the average low-temperature is 29.7°F (-1.3°C).

Humidity

Months with the highest humidity in Summit, New Jersey, are February and December, with an average relative humidity of 80%.

Rainfall

In December, in Summit, the rain falls for 11.6 days. Throughout December, 3.03" (77mm) of precipitation is accumulated. Throughout the year, there are 164.2 rainfall days, and 30.67" (779mm) of precipitation is accumulated.

Snowfall

January through May, October through December are months with snowfall in Summit. In Summit, in December, during 4 snowfall days, 1.61" (41mm) of snow is typically accumulated. In Summit, during the entire year, snow falls for 26 days, and aggregates up to 11.61" (295mm) of snow.

Daylight

With an average of 9.3h of daylight, December has the shortest days of the year.

Sunshine

In Summit, New Jersey, the average sunshine 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 Summit. A UV Index of 2, and less, symbolizes a minimal health vulnerability from the exposure to the Sun's UV rays for the average person.
Note: In December, the average maximum UV index of 2 translate into the following recommendations:
Most people can stay in the Sun for up to 1 hour without burning, apart from children that always must be protected from sun exposure. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. A wide-brim hat offers excellent sun protection for eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun. Caution! The reflection of snow can nearly double the intensity of the Sun's UV radiation.

What is the temperature in December in Summit?

In Summit, New Jersey, in December, the average high-temperature is 40.8°F (4.9°C), and the average low-temperature is 29.7°F (-1.3°C).

What are the most humid months in Summit?

February and December, with an average relative humidity of 80%, are most humid months in Summit.

What is the average humidity in December in Summit?

The average relative humidity in December in Summit is 80%.

How much does it rain in Summit in December?

In Summit, in December, during 11.6 rainfall days, 3.03" (77mm) of precipitation is typically accumulated.

How much does it snow in Summit in December?

In Summit, during December, snow falls for 4 days and regularly aggregates up to 1.61" (41mm) of snow.

What is the month with the shortest days in Summit?

The month with the shortest days in Summit is December, with an average of 9.3h of daylight.

How many hours of daylight does Summit have in December?

The average length of the day in December in Summit, New Jersey, is 9.3h.

How many hours of sunshine does Summit have in December?

In Summit, New Jersey, the average sunshine in December is 4.8h.

When is the lowest UV index in Summit?

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

What is the UV index reading in December in Summit?

In December, the average daily maximum UV index in Summit, New Jersey, is 2. A UV Index estimate of 2, and below, represents a low health risk from the exposure to the Sun's UV rays.
Average temperature in December - Summit, NJ
  • Average high temperature in December: 40.8°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: 29.7°F

The month with the highest average low temperature is July (65.7°F).
The coldest month (with the lowest average low temperature) is January (22.5°F).

Average pressure in December - Summit, NJ
  • Average pressure in December: 30.08"

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

Average wind speed in December - Summit, NJ
  • Average wind speed in December: 7.6mph

The windiest month (with the highest average wind speed) is March (8.5mph).
The calmest month (with the lowest average wind speed) is August (5.3mph).

Average humidity in December - Summit, NJ
  • Average humidity in December: 80%

Months with the highest relative humidity are February and December (80%).
Months with the lowest relative humidity are April and August (74%).

Average rainfall in December - Summit, NJ
  • Average rainfall in December: 3.03"

The wettest month (with the highest rainfall) is July (3.27").
The driest month (with the least rainfall) is September (1.69").

Average rainfall days in December - Summit, NJ
  • Average rainfall days in December: 11.6 days

The month with the highest number of rainy days is July (17.4 days).
The month with the least rainy days is January (8.8 days).

Average snowfall in December - Summit, NJ
  • Average snowfall in December: 1.61"

The month with the highest snowfall is March (3.5").
Months with the least snowfall are June, July, August and September (0").

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

The month with the highest number of snowfall days is January (7.6 days).
Months with the least snowfall days are June, July, August and September (0 days).

Average daylight in December / Average sunshine in December - Summit, NJ
  • Average daylight in December: 9.3h

The month with the longest days is June (Average daylight: 15.1h).
The month with the shortest days is December (Average daylight: 9.3h).

  • Average sunshine in December: 4.8h

The month with the most sunshine is July (Average sunshine: 10.3h).
The month with the least sunshine is February (Average sunshine: 4.6h).

Average sunshine days in December - Summit, NJ
  • Average sunshine days in December: 15.6 days

The month with the most sunshine days is November (18.3 days).
The month with the least sunshine days is June (10.5 days).

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

Months with the highest UV index are June, July and August (UV index 6).
Months with the lowest UV index are January, February, March, November and December (UV index 2).

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

Months with the most cloud cover are February and March (Cloud cover 49).
Months with the least cloud cover are July and August (Cloud cover 34).

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

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