December weather forecastGreen Rock, IL
December
Weather in December
The first month of the winter, December, is also a wintry month in Green Rock, Illinois, with temperature in the range of an average low of 23.9°F (-4.5°C) and an average high of 34.5°F (1.4°C).Temperature
The onset of December entails a temperature shift, as the average high-temperature decreases from a chilly 46.9°F (8.3°C) in November to a cold 34.5°F (1.4°C). December brings an average low-temperature of 23.9°F (-4.5°C) to Green Rock.Humidity
In December, the average relative humidity is 81%.Rainfall
December is the month with the least rainfall. Rain falls for 4.1 days and accumulates 0.35" (9mm) of precipitation.Snowfall
Months with snowfall are January through April, September through December. In Green Rock, in December, during 5 snowfall days, 0.39" (10mm) of snow is typically accumulated. Throughout the year, there are 24.5 snowfall days, and 4.09" (104mm) of snow is accumulated.Daylight
With an average of 9h and 12min of daylight, December has the shortest days of the year.On the first day of the month, sunrise is at 7:08 am and sunset at 4:32 pm. On the last day of December, sunrise is at 7:27 am and sunset at 4:41 pm CST.
Sunshine
The average sunshine in December is 4.2h.UV index
In December, the average daily maximum UV index is 2. A UV Index reading of 2, and below, represents a minimal health vulnerability from exposure to the Sun's UV rays for the average person.Note: The maximum daily UV index of 2 in December converts into the following recommendations:
Many can withstand an hour in the sun without burning, yet children must always have protection against sunlight. To prevent harmful UV exposure, minimize direct contact with the Sun around midday. A hat with a broad brim is indispensable, filtering out up to half of UV rays. Be vigilant! The reflective nature of snow can increase the Sun's UV radiation nearly twofold.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Green Rock, IL
- Average high temperature in December: 34.5°F
The warmest month (with the highest average high temperature) is July (81.7°F).
The month with the lowest average high temperature is January (28.2°F).
- Average low temperature in December: 23.9°F
The month with the highest average low temperature is July (64.8°F).
The coldest month (with the lowest average low temperature) is January (15.4°F).
Average pressure in December
Green Rock, IL
- Average pressure in December: 30.11"Hg
The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).
Average wind speed in December
Green Rock, IL
- Average wind speed in December: 9.8mph
The windiest month (with the highest average wind speed) is April (10.6mph).
The calmest month (with the lowest average wind speed) is August (6.7mph).
Average humidity in December
Green Rock, IL
- Average humidity in December: 81%
The months with the highest relative humidity are January and July (83%).
The month with the lowest relative humidity is October (71%).
Average rainfall in December
Green Rock, IL
- Average rainfall in December: 0.35"
The wettest month (with the highest rainfall) is May (1.61").
The driest month (with the least rainfall) is December (0.35").
Average rainfall days in December
Green Rock, IL
- Average rainfall days in December: 4.1 days
The month with the highest number of rainy days is May (13.4 days).
The month with the least rainy days is January (3.2 days).
Average snowfall in December
Green Rock, IL
- Average snowfall in December: 0.39"
The month with the highest snowfall is January (1.26").
The months with the least snowfall are May, June, July and August (0").
Average snowfall days in December
Green Rock, IL
- Average snowfall days in December: 5 days
The month with the highest number of snowfall days is January (7.2 days).
The months with the least snowfall days are May, June, July and August (0 days).
Average daylight in December /
Average sunshine in December
Green Rock, IL
- Average daylight in December: 9h and 12min
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 12min).
- Average sunshine in December: 4h and 12min
The month with the most sunshine is July (Average sunshine: 10h and 6min).
The month with the least sunshine is January (Average sunshine: 3h and 54min).
Average sunshine days in December
Green Rock, IL
- Average sunshine days in December: 22.4 days
The month with the most sunshine days is December (22.4 days).
The month with the least sunshine days is June (14.4 days).
Average UV index in December
Green Rock, IL
- Average UV index in December: 2
The month with the highest UV index is July (UV index 6).
The month with the lowest UV index is January (UV index 1).
Average cloud cover in December
Green Rock, IL
- Average cloud cover in December: 56
The month with the most cloud cover is January (Cloud cover 58).
The month with the least cloud cover is August (Cloud cover 30).
Average visibility in December
Green Rock, IL
- 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).
