December weather forecastSouth River, NJ
December
Weather in December
The first month of the winter, December, is also a frosty month in South River, New Jersey, with an average temperature varying between 43.3°F (6.3°C) and 32.7°F (0.4°C).Temperature
South River's transition into December involves a gentle shift in temperature, receding from a fresh 52.2°F (11.2°C) in November to a frosty 43.3°F (6.3°C). In South River, the average low-temperature during the month of December is an icy 32.7°F (0.4°C).Humidity
The months with the highest humidity are February, May, October and December, with an average relative humidity of 77%.Rainfall
In South River, in December, during 10.6 rainfall days, 3.11" (79mm) of precipitation is typically accumulated. In South River, during the entire year, the rain falls for 154 days and collects up to 30.75" (781mm) of precipitation.Snowfall
Months with snowfall are January through April, November and December. In South River, during December, snow falls for 3.1 days and regularly aggregates up to 1.02" (26mm) of snow. Throughout the year, there are 18.1 snowfall days, and 8.35" (212mm) of snow is accumulated.Daylight
With an average of 9h and 18min of daylight, December has the shortest days of the year.On the first day of December, sunrise is at 7:02 am and sunset at 4:31 pm. On the last day of the month, sunrise is at 7:20 am and sunset at 4:41 pm EST.
Sunshine
In South River, 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. A UV Index value of 2, and less, symbolizes a minimal health hazard from unsafe exposure to UV radiation for ordinary individuals.Note: A daily maximum UV index of 2 in December translates into the following instructions:
While sun exposure does not greatly affect most, individuals with fair skin, babies, and children always need vigilant safeguarding. To avoid the Sun's strongest rays, limit exposure around the mid-day period. Counter UV radiation's ill effects with clothing designed for sun safety and UV-resistant eyewear. On your guard! Snow's reflection can almost double the intensity of the Sun's UV radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
South River, NJ
- Average high temperature in December: 43.3°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 (36.9°F).
- Average low temperature in December: 32.7°F
The month with the highest average low temperature is July (68.7°F).
The coldest month (with the lowest average low temperature) is January (25.7°F).
Average pressure in December
South River, 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).
Average wind speed in December
South River, NJ
- Average wind speed in December: 8.9mph
The windiest months (with the highest average wind speed) are January and March (9.6mph).
The calmest month (with the lowest average wind speed) is July (6.2mph).
Average humidity in December
South River, NJ
- Average humidity in December: 77%
The months with the highest relative humidity are February, May, October and December (77%).
The months with the lowest relative humidity are April and August (73%).
Average rainfall in December
South River, NJ
- Average rainfall in December: 3.11"
The wettest month (with the highest rainfall) is July (3.58").
The driest month (with the least rainfall) is September (1.81").
Average rainfall days in December
South River, NJ
- Average rainfall days in December: 10.6 days
The month with the highest number of rainy days is July (17.4 days).
The months with the least rainy days are January and November (8.5 days).
Average snowfall in December
South River, NJ
- Average snowfall in December: 1.02"
The month with the highest snowfall is March (3.82").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
South River, NJ
- Average snowfall days in December: 3.1 days
The month with the highest number of snowfall days is February (5.1 days).
The months with the least snowfall days are May, June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
South River, NJ
- Average daylight in December: 9h and 18min
The month with the longest days is June (Average daylight: 15h and 0min).
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 30min).
The month with the least sunshine is February (Average sunshine: 4h and 42min).
Average sunshine days in December
South River, NJ
- Average sunshine days in December: 18 days
The month with the most sunshine days is November (20 days).
The month with the least sunshine days is July (10.5 days).
Average UV index in December
South River, NJ
- Average UV index in December: 2
The months with the highest UV index are May, 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
South River, NJ
- Average cloud cover in December: 48
The months with the most cloud cover are February and December (Cloud cover 48).
The months with the least cloud cover are July and August (Cloud cover 31).
Average visibility in December
South River, NJ
- 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).
