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 comes with a decrease in the average high-temperature, falling from a fresh 50°F (10°C) in November to an icy 38.7°F (3.7°C). In Williamsville, the average low-temperature during the month of December is a freezing cold 28.2°F (-2.1°C).Humidity
In December, the average relative humidity is 78%.Rainfall
December is the month with the least rainfall. Rain falls for 6.6 days and accumulates 0.83" (21mm) of precipitation.Snowfall
January through April, November and December are months with snowfall. In Williamsville, in December, snow falls for 4.8 days, with typically accumulated 0.59" (15mm) of snow. In Williamsville, Illinois, during the entire year, snow falls for 24.5 days and aggregates up to 5.51" (140mm) of snow.Daylight
With an average of 9h and 24min of daylight, December has the shortest days of the year.On the first day of the month, sunrise is at 7:01 am and sunset at 4:33 pm. On the last day of December, sunrise is at 7:19 am and sunset at 4:43 pm CST.
Sunshine
In Williamsville, the average sunshine in December is 4.7h.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 reading of 2, and below, represents a low health risk from unprotected exposure to Sun's UV rays for the ordinary person.Note: In December, the maximum UV index of 2 suggests this advice:
Most people face no serious problems with extended sun exposure, but those with fair skin, infants, and children always need protection. Given the potency of the midday Sun's UV radiation, one should avoid prolonged exposure. Combat UV radiation's detrimental effects with sun-safe clothing and UV-blocking eyewear. Beware! Reflection from snow can magnify the Sun's UV radiation nearly twofold.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How cold is it in December?
What is the average humidity in December?
What is the driest month?
How many days does it rain in December?
How much does it snow in December?
What is the month with the shortest days?
What is the average length of the day in December?
When are sunrise and sunset in December?
How many hours of sunshine does Williamsville have in December?
What are the months with the lowest UV index?
What is the UV index intensity in December?
Average temperature in December
Williamsville, IL
- Average high temperature in December: 38.7°F
The warmest month (with the highest average high temperature) is July (82.8°F).
The month with the lowest average high temperature is January (33.1°F).
- Average low temperature in December: 28.2°F
The month with the highest average low temperature is July (66°F).
The coldest month (with the lowest average low temperature) is January (20.8°F).
Average pressure in December
Williamsville, IL
- Average pressure in December: 30.12"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).
Average wind speed in December
Williamsville, IL
- Average wind speed in December: 9.8mph
The windiest months (with the highest average wind speed) are January and April (10.4mph).
The calmest months (with the lowest average wind speed) are July and August (6.2mph).
Average humidity in December
Williamsville, IL
- Average humidity in December: 78%
The month with the highest relative humidity is July (84%).
The month with the lowest relative humidity is October (70%).
Average rainfall in December
Williamsville, IL
- Average rainfall in December: 0.83"
The wettest month (with the highest rainfall) is June (2.36").
The driest month (with the least rainfall) is December (0.83").
Average rainfall days in December
Williamsville, IL
- Average rainfall days in December: 6.6 days
The month with the highest number of rainy days is May (17 days).
The month with the least rainy days is February (5.7 days).
Average snowfall in December
Williamsville, IL
- Average snowfall in December: 0.59"
The month with the highest snowfall is January (1.81").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
Williamsville, IL
- Average snowfall days in December: 4.8 days
The month with the highest number of snowfall days is January (8 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
Williamsville, IL
- Average daylight in December: 9h and 2min
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 24min).
- Average sunshine in December: 4h and 4min
The month with the most sunshine is June (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 4h and 6min).
Average sunshine days in December
Williamsville, IL
- Average sunshine days in December: 20.5 days
The month with the most sunshine days is December (20.5 days).
The month with the least sunshine days is May (11.5 days).
Average UV index in December
Williamsville, 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
Williamsville, IL
- Average cloud cover in December: 51
The month with the most cloud cover is January (Cloud cover 55).
The months with the least cloud cover are June, August and September (Cloud cover 30).
Average visibility in December
Williamsville, IL
- Average visibility in December: 6mi
The months with the highest visibility are January, February, March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are July and August (5mi).
Williamsville, Illinois, USA
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