December weather forecastIlliopolis, IL
December
Weather in December
The first month of the winter, December, is still a cold month in Illiopolis, Illinois, with an average temperature fluctuating between 27.5°F (-2.5°C) and 38.3°F (3.5°C).Temperature
The shift from November to December corresponds with a decrease in the average high-temperature, down to a wintry 38.3°F (3.5°C) from a frosty 49.8°F (9.9°C). During the month of December, an average low-temperature of 27.5°F (-2.5°C) is recorded.Humidity
The average relative humidity in December is 79%.Rainfall
December is the month with the least rainfall. Rain falls for 8.3 days and accumulates 1.1" (28mm) of precipitation.Snowfall
January through April, November and December are months with snowfall. In Illiopolis, in December, during 6.7 snowfall days, 1.02" (26mm) of snow is typically accumulated. In Illiopolis, during the entire year, snow falls for 29.7 days and aggregates up to 7.13" (181mm) of snow.Daylight
The month with the shortest days is December, with an average of 9h and 24min of daylight.On the first day of the month, sunrise is at 6:59 am and sunset at 4:32 pm. On the last day of December, sunrise is at 7:18 am and sunset at 4:42 pm CST.
Sunshine
The average sunshine in December is 4.5h.UV index
In December, the average daily maximum UV index is 2. A UV Index value of 2, and less, symbolizes a minimal health hazard from unsafe exposure to UV radiation for ordinary individuals.Note: The UV index of 2 in December translates into these instructions:
People with sensitive skin, children, and babies should always be protected from prolonged sun exposure. The intensity of the Sun's UV radiation during midday suggests reducing time spent outdoors. Your best bet for sun defense on the face, eyes, and neck is a hat with a wide brim. Mind you! Snow reflection can increase the intensity of 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
Illiopolis, IL
- Average high temperature in December: 38.3°F
The warmest month (with the highest average high temperature) is July (82°F).
The month with the lowest average high temperature is January (32.5°F).
- Average low temperature in December: 27.5°F
The month with the highest average low temperature is July (65.7°F).
The coldest month (with the lowest average low temperature) is January (20.5°F).
Average pressure in December
Illiopolis, 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 (29.92"Hg).
Average wind speed in December
Illiopolis, IL
- Average wind speed in December: 9.8mph
The windiest month (with the highest average wind speed) is April (10.6mph).
The calmest months (with the lowest average wind speed) are July and August (6.3mph).
Average humidity in December
Illiopolis, IL
- Average humidity in December: 79%
The month with the highest relative humidity is July (84%).
The month with the lowest relative humidity is October (70%).
Average rainfall in December
Illiopolis, IL
- Average rainfall in December: 1.1"
The wettest month (with the highest rainfall) is May (2.68").
The driest month (with the least rainfall) is December (1.1").
Average rainfall days in December
Illiopolis, IL
- Average rainfall days in December: 8.3 days
The month with the highest number of rainy days is May (17 days).
The months with the least rainy days are January and February (6.3 days).
Average snowfall in December
Illiopolis, IL
- Average snowfall in December: 1.02"
The month with the highest snowfall is January (2.24").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
Illiopolis, IL
- Average snowfall days in December: 6.7 days
The month with the highest number of snowfall days is January (9.4 days).
The months with the least snowfall days are May, June, July and August (0 days).
Average daylight in December /
Average sunshine in December
Illiopolis, IL
- Average daylight in December: 9h and 24min
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 30min
The month with the most sunshine is June (Average sunshine: 10h and 12min).
The month with the least sunshine is January (Average sunshine: 4h and 0min).
Average sunshine days in December
Illiopolis, IL
- Average sunshine days in December: 17.1 days
The month with the most sunshine days is November (18.9 days).
The month with the least sunshine days is May (10.8 days).
Average UV index in December
Illiopolis, IL
- Average UV index in December: 2
The months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is January (UV index 1).
Average cloud cover in December
Illiopolis, IL
- Average cloud cover in December: 53
The month with the most cloud cover is January (Cloud cover 57).
The months with the least cloud cover are June and September (Cloud cover 31).
Average visibility in December
Illiopolis, 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).
