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 start of December involves a temperature drop, moving from a chilly 48.6°F (9.2°C) in November to an icy 38.8°F (3.8°C). Willow Brook experiences an average low-temperature of 27.1°F (-2.7°C) in the month of December.Humidity
The months with the highest humidity are February, October and December, with an average relative humidity of 81%.Rainfall
In Willow Brook, in December, during 7.5 rainfall days, 1.14" (29mm) of precipitation is typically accumulated. In Willow Brook, during the entire year, the rain falls for 131.1 days and collects up to 13.31" (338mm) of precipitation.Snowfall
Months with snowfall in Willow Brook are January through May, October through December. In Willow Brook, during December, snow falls for 4.5 days and regularly aggregates up to 1.18" (30mm) of snow. In Willow Brook, during the entire year, snow falls for 25.8 days and aggregates up to 6.89" (175mm) of snow.Daylight
The month with the shortest days is December, with an average of 9h and 18min of daylight.On the first day of the month, sunrise is at 7:04 am and sunset at 4:29 pm. On the last day of December, sunrise is at 7:22 am and sunset at 4:38 pm EST.
Sunshine
The average sunshine in December is 4.7h.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 estimate of 2, and below, represents a minimal health vulnerability from exposure to the Sun's UV rays for the ordinary person.Note: The UV index of 2 during December translates into the following guidance:
It is important to always shield children, babies, and individuals with sensitive skin from prolonged exposure to the sun. Direct exposure to the Sun's intense radiation around midday should be avoided for health reasons. A hat with a broad brim is indispensable, filtering out up to half of UV rays. Mind this! Nearly twice the UV radiation from the Sun can be reflected by the snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Is December cold?
What is the most humid month?
What is the average humidity in December?
How many days does it rain in December?
How many days does it snow in December?
What is the month with the shortest days?
How many hours of daylight does Willow Brook have in December?
When are sunrise and sunset in December?
How long on average sun shines in December?
What are the months with the lowest UV index?
How high is the UV index in December?
Average temperature in December
Willow Brook, NJ
- Average high temperature in December: 38.8°F
The warmest month (with the highest average high temperature) is July (82.9°F).
The month with the lowest average high temperature is January (33.3°F).
- Average low temperature in December: 27.1°F
The month with the highest average low temperature is July (62.1°F).
The coldest month (with the lowest average low temperature) is January (20.5°F).
Average pressure in December
Willow Brook, NJ
- Average pressure in December: 30.07"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
Willow Brook, NJ
- Average wind speed in December: 6.8mph
The windiest months (with the highest average wind speed) are January and March (7.5mph).
The calmest month (with the lowest average wind speed) is August (4.7mph).
Average humidity in December
Willow Brook, NJ
- Average humidity in December: 81%
The months with the highest relative humidity are February, October and December (81%).
The month with the lowest relative humidity is April (76%).
Average rainfall in December
Willow Brook, NJ
- Average rainfall in December: 1.14"
The wettest month (with the highest rainfall) is July (1.77").
The driest month (with the least rainfall) is September (0.63").
Average rainfall days in December
Willow Brook, NJ
- Average rainfall days in December: 7.5 days
The month with the highest number of rainy days is July (15.8 days).
The month with the least rainy days is January (5.8 days).
Average snowfall in December
Willow Brook, NJ
- Average snowfall in December: 1.18"
The month with the highest snowfall is March (1.69").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
Willow Brook, NJ
- Average snowfall days in December: 4.5 days
The month with the highest number of snowfall days is February (7.3 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Willow Brook, 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 4min
The month with the most sunshine is July (Average sunshine: 10h and 18min).
The month with the least sunshine is February (Average sunshine: 4h and 24min).
Average sunshine days in December
Willow Brook, NJ
- Average sunshine days in December: 19.2 days
The months with the most sunshine days are January and November (20.4 days).
The month with the least sunshine days is June (12.5 days).
Average UV index in December
Willow Brook, NJ
- Average UV index in December: 2
The month with the highest UV index is June (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
Willow Brook, NJ
- Average cloud cover in December: 50
The month with the most cloud cover is February (Cloud cover 51).
The months with the least cloud cover are July and August (Cloud cover 35).
Average visibility in December
Willow Brook, NJ
- Average visibility in December: 5mi
The months with the highest visibility are April and November (6mi).
The months with the lowest visibility are January, February, March, May, June, July, August, September, October and December (5mi).
Willow Brook, New Jersey, USA
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