Contents
- Weather in December
- Frequently asked questions
- Average temperature in December
- Average pressure in December
- Average wind speed in December
- Average humidity in December
- Average rainfall in December
- Average rainfall days in December
- Average snowfall in December
- Average snowfall days in December
- Average daylight in December
- Average sunshine in December
- Average sunshine days in December
- Average UV index in December
- Average cloud cover in December
- Average visibility in December
Weather in December
Temperature
The onset of December comes with a shift in the average high-temperature, falling from a fresh 53.4°F (11.9°C) in November to a frosty 44.2°F (6.8°C). Williamstown's average low-temperature in December is measured at an icy 32.9°F (0.5°C).Humidity
In Williamstown, New Jersey, the average relative humidity in December is 77%.Rainfall
December is the month with the most rainfall. Rain falls for 11 days and accumulates 3.35" (85mm) of precipitation.Snowfall
Months with snowfall in Williamstown are January through May, November and December. In Williamstown, in December, snow falls for 3 days, with typically accumulated 1.26" (32mm) of snow. Throughout the year, there are 17.8 snowfall days, and 10.28" (261mm) of snow is accumulated.Daylight
The month with the shortest days in Williamstown is December, with an average of 9h and 24min of daylight.On the first day of the month, sunrise is at 7:02 am and sunset at 4:36 pm. On the last day of December, sunrise is at 7:20 am and sunset at 4:45 pm EST.
Sunshine
In December, the average sunshine in Williamstown is 5.2h.UV index
January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index estimate of 2, and below, represents a low threat to health from exposure to the Sun's UV radiation for the ordinary person.Note: The UV index of 2 in December translates into these instructions:
Babies, children, and those with sensitive skin should always avoid extended periods in the sun. Around midday, solar radiation is most harmful; hence, exposure should be limited. To cut down UV radiation exposure by about half, sport a wide-brim hat. Consider this! The reflection from 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
How cold is December in Williamstown?
What is the average humidity in December in Williamstown?
What is the rainiest month in Williamstown?
How much does it rain in Williamstown in December?
How much does it snow in Williamstown in December?
What is the month with the shortest days in Williamstown?
How many hours of daylight does Williamstown have in December?
When is the sunrise / sunset in December in Williamstown?
How many hours of sunshine does Williamstown have in December?
When is the lowest UV index in Williamstown?
What is the UV index reading in December in Williamstown?
Average temperature in December
Williamstown, NJ
- Average high temperature in December: 44.2°F
The warmest month (with the highest average high temperature) is July (85.3°F).
The month with the lowest average high temperature is January (38.1°F).
- Average low temperature in December: 32.9°F
The month with the highest average low temperature is July (68.5°F).
The coldest month (with the lowest average low temperature) is January (26.8°F).
Average pressure in December
Williamstown, NJ
- Average pressure in December: 30.09"Hg
The month with the highest atmospheric pressure is November (30.12"Hg).
The month with the lowest atmospheric pressure is June (29.94"Hg).
Average wind speed in December
Williamstown, NJ
- Average wind speed in December: 7.8mph
The windiest month (with the highest average wind speed) is April (8.7mph).
The calmest month (with the lowest average wind speed) is August (5.7mph).
Average humidity in December
Williamstown, NJ
- Average humidity in December: 77%
The month with the highest relative humidity is October (78%).
The month with the lowest relative humidity is April (71%).
Average rainfall in December
Williamstown, NJ
- Average rainfall in December: 3.35"
The wettest month (with the highest rainfall) is December (3.35").
The driest month (with the least rainfall) is September (1.73").
Average rainfall days in December
Williamstown, NJ
- Average rainfall days in December: 11 days
The month with the highest number of rainy days is July (16.9 days).
The month with the least rainy days is January (8.8 days).
Average snowfall in December
Williamstown, NJ
- Average snowfall in December: 1.26"
The month with the highest snowfall is March (3.54").
The months with the least snowfall are June, July, August, September and October (0").
Average snowfall days in December
Williamstown, NJ
- Average snowfall days in December: 3 days
The month with the highest number of snowfall days is January (5.5 days).
The months with the least snowfall days are June, July, August, September and October (0 days).
Average daylight in December /
Average sunshine in December
Williamstown, NJ
- Average daylight in December: 9h and 2min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in December: 5h and 1min
The month with the most sunshine is July (Average sunshine: 10h and 48min).
The month with the least sunshine is February (Average sunshine: 4h and 54min).
Average sunshine days in December
Williamstown, NJ
- Average sunshine days in December: 17.9 days
The month with the most sunshine days is November (19.5 days).
The month with the least sunshine days is July (11.8 days).
Average UV index in December
Williamstown, 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, November and December (UV index 2).
Average cloud cover in December
Williamstown, NJ
- Average cloud cover in December: 45
The months with the most cloud cover are February and March (Cloud cover 46).
The months with the least cloud cover are July and August (Cloud cover 30).
Average visibility in December
Williamstown, 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).
Williamstown, New Jersey, USA
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