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
December is characterized by a reduction in the average high-temperature, from a fresh 51.6°F (10.9°C) in November to a cold 40.3°F (4.6°C). Williamson's nights in December experience an average temperature drop to a freezing cold 29.1°F (-1.6°C).Humidity
In Williamson, the average relative humidity in December is 78%.Rainfall
In Williamson, in December, it is raining for 6.7 days, with typically 0.87" (22mm) of accumulated precipitation. In Williamson, during the entire year, the rain falls for 121.4 days and collects up to 14.72" (374mm) of precipitation.Snowfall
Months with snowfall are January through March, November and December. The month with the most snowfall is December, when snow falls for 3.8 days and typically aggregates up to 0.98" (25mm) of snow.Daylight
With an average of 9h and 30min of daylight, December has the shortest days of the year.On the first day of the month, sunrise is at 6:59 am and sunset at 4:37 pm. On the last day of December, in Williamson, sunrise is at 7:17 am and sunset at 4:47 pm CST.
Sunshine
In December, the average sunshine is 4.8h.UV index
The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 2. A UV Index estimate of 2, and below, represents a minimal health vulnerability from exposure to the Sun's UV rays for ordinary individuals.Note: An average maximum UV index of 2 in December leads to these recommendations:
Unlike children, who always need sun protection, most individuals can remain in the sun for up to an hour without getting burnt. Protect yourself from the midday Sun's peak UV radiation by minimizing exposure. Enhance your sun protection with tightly woven, yet airy clothing. Be watchful! The reflection of snow can enhance the intensity of the Sun's UV radiation nearly double.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How cold does it get in December?
What is the average humidity in December?
How much does it rain in December?
What is the snowiest month?
How much does it snow in December?
What is the month with the shortest days?
How many hours of daylight does Williamson have in December?
What time are sunrise and sunset in December?
How many hours of sunshine does Williamson have in December?
What are the months with the lowest UV index in Williamson?
How high is the UV index in December?
Average temperature in December
Williamson, IL
- Average high temperature in December: 40.3°F
The warmest month (with the highest average high temperature) is July (84.2°F).
The month with the lowest average high temperature is January (35.6°F).
- Average low temperature in December: 29.1°F
The month with the highest average low temperature is July (67.5°F).
The coldest month (with the lowest average low temperature) is January (22.6°F).
Average pressure in December
Williamson, IL
- Average pressure in December: 30.13"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in December
Williamson, IL
- Average wind speed in December: 9.3mph
The windiest month (with the highest average wind speed) is January (10mph).
The calmest month (with the lowest average wind speed) is July (5.8mph).
Average humidity in December
Williamson, IL
- Average humidity in December: 78%
The month with the highest relative humidity is July (81%).
The month with the lowest relative humidity is October (71%).
Average rainfall in December
Williamson, IL
- Average rainfall in December: 0.87"
The wettest month (with the highest rainfall) is June (1.89").
The driest month (with the least rainfall) is February (0.67").
Average rainfall days in December
Williamson, IL
- Average rainfall days in December: 6.7 days
The month with the highest number of rainy days is July (14 days).
The month with the least rainy days is January (5.8 days).
Average snowfall in December
Williamson, IL
- Average snowfall in December: 0.98"
The month with the highest snowfall is December (0.98").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in December
Williamson, IL
- Average snowfall days in December: 3.8 days
The month with the highest number of snowfall days is January (6.3 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
Williamson, IL
- Average daylight in December: 9h and 3min
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 30min).
- Average sunshine in December: 4h and 5min
The months with the most sunshine are June and July (Average sunshine: 10h and 18min).
The month with the least sunshine is January (Average sunshine: 4h and 24min).
Average sunshine days in December
Williamson, IL
- Average sunshine days in December: 20.5 days
The month with the most sunshine days is January (20.9 days).
The month with the least sunshine days is July (12.5 days).
Average UV index in December
Williamson, IL
- Average UV index in December: 2
The months with the highest UV index are 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
Williamson, IL
- Average cloud cover in December: 50
The month with the most cloud cover is January (Cloud cover 52).
The months with the least cloud cover are June, July, August and September (Cloud cover 29).
Average visibility in December
Williamson, 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).
Williamson, Illinois, USA
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