December weather forecastRock Mill, NJ
December
Weather in December
December, the first month of the winter in Rock Mill, is also a wintry month, with an average temperature fluctuating between 31.1°F (-0.5°C) and 42.4°F (5.8°C).Temperature
December's onset brings a reduction in the average high-temperature, from a cool 51.6°F (10.9°C) in November to a wintry 42.4°F (5.8°C). The month of December records an average low-temperature of 31.1°F (-0.5°C).Humidity
In December, the average relative humidity in Rock Mill, New Jersey, is 78%.Rainfall
In December, in Rock Mill, the rain falls for 7.5 days. Throughout December, 0.98" (25mm) of precipitation is accumulated. In Rock Mill, during the entire year, the rain falls for 107.3 days and collects up to 8.82" (224mm) of precipitation.Snowfall
Months with snowfall are January through May, November and December. In December, in Rock Mill, it is snowing for 2.5 days. Throughout December, 0.43" (11mm) of snow is accumulated. Throughout the year, there are 15.5 snowfall days, and 2.76" (70mm) of snow is accumulated.Daylight
December has the shortest days of the year in Rock Mill, New Jersey, 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 4:33 pm. On the last day of December, sunrise is at 7:21 am and sunset at 4:42 pm EST.
Sunshine
In December, the average sunshine is 4.9h.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 low health risk from unprotected exposure to Sun's UV rays for the average person.Note: The maximum UV index of 2 during December translates into these guidelines:
Although prolonged sun exposure does not typically bother most people, children, babies, and those with sensitive skin should always have protection. Avoiding the Sun during its peak radiation time around midday is a healthy practice. For minimizing sun-related eye damage, always choose sunglasses with UVA and UVB coverage. Consider carefully! The reflective quality of snow 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
Rock Mill, NJ
- Average high temperature in December: 42.4°F
The warmest month (with the highest average high temperature) is July (84.6°F).
The month with the lowest average high temperature is January (36.5°F).
- Average low temperature in December: 31.1°F
The month with the highest average low temperature is July (66.7°F).
The coldest month (with the lowest average low temperature) is January (23.5°F).
Average pressure in December
Rock Mill, NJ
- Average pressure in December: 30.09"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
Rock Mill, NJ
- Average wind speed in December: 7.8mph
The windiest month (with the highest average wind speed) is March (8.6mph).
The calmest month (with the lowest average wind speed) is August (5.3mph).
Average humidity in December
Rock Mill, NJ
- Average humidity in December: 78%
The months with the highest relative humidity are February and October (79%).
The month with the lowest relative humidity is April (74%).
Average rainfall in December
Rock Mill, NJ
- Average rainfall in December: 0.98"
The wettest month (with the highest rainfall) is July (1.18").
The driest month (with the least rainfall) is September (0.35").
Average rainfall days in December
Rock Mill, NJ
- Average rainfall days in December: 7.5 days
The month with the highest number of rainy days is July (12.9 days).
The month with the least rainy days is November (5.5 days).
Average snowfall in December
Rock Mill, NJ
- Average snowfall in December: 0.43"
The month with the highest snowfall is March (0.75").
The months with the least snowfall are June, July, August, September and October (0").
Average snowfall days in December
Rock Mill, NJ
- Average snowfall days in December: 2.5 days
The month with the highest number of snowfall days is February (4.3 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Rock Mill, 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 36min).
The month with the least sunshine is February (Average sunshine: 4h and 42min).
Average sunshine days in December
Rock Mill, NJ
- Average sunshine days in December: 21.2 days
The month with the most sunshine days is November (22.7 days).
The month with the least sunshine days is July (13.6 days).
Average UV index in December
Rock Mill, 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
Rock Mill, 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 33).
Average visibility in December
Rock Mill, NJ
- Average visibility in December: 6mi
The 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).
