December weather forecastDeKalb, IL
December
Weather in December
December infuses the air of DeKalb, Illinois, with the crisp winter chill. The most significant change in this month's weather is the increase in snowfall from 1.81" (46mm) to 2.91" (74mm). Streets are often snow-covered, with festive decorations twinkling against the white background. The markedly shorter daylight hours and a considerable dip in temperatures contribute to the general holiday mood. Simply put, December's weather culminates the year with a quintessential winter charm.Temperature
A change in temperatures is noted as November gives way to December, with average highs reducing from a chilly 45.3°F (7.4°C) to a wintry 33.1°F (0.6°C). An average low-temperature of 23°F (-5°C) is noted during the month of December.Humidity
In DeKalb, the average relative humidity in December is 83%.Rainfall
In DeKalb, in December, it is raining for 8.5 days, with typically 1.69" (43mm) of accumulated precipitation. In DeKalb, during the entire year, the rain falls for 152.6 days and collects up to 32.09" (815mm) of precipitation.Snowfall
Months with snowfall are January through May, October through December. In DeKalb, in December, snow falls for 10 days, with typically accumulated 2.91" (74mm) of snow. In DeKalb, during the entire year, snow falls for 44.3 days and aggregates up to 17.87" (454mm) of snow.Daylight
December has the shortest days of the year, with an average of 9h and 12min of daylight.On the first day of December, sunrise is at 7:03 am and sunset at 4:24 pm. On the last day of the month, sunrise is at 7:22 am and sunset at 4:33 pm CST.
Sunshine
In December, the average sunshine is 3.9h.UV index
The months with the lowest UV index are January and December, with an average maximum UV index of 1. A UV Index estimate of 2, and below, represents a minimal health vulnerability from exposure to the Sun's UV radiation for average individuals.Note: The maximum daily UV index of 1 in December converts into the following recommendations:
Although the majority can endure up to an hour in the sun without burns, children always require sun protection. Stay safe from the Sun's strongest UV rays by limiting exposure during midday. 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
Average temperature in December
DeKalb, IL
- Average high temperature in December: 33.1°F
The warmest month (with the highest average high temperature) is July (80.2°F).
The month with the lowest average high temperature is January (27°F).
- Average low temperature in December: 23°F
The month with the highest average low temperature is July (63.1°F).
The coldest month (with the lowest average low temperature) is January (15.1°F).
Average pressure in December
DeKalb, IL
- Average pressure in December: 30.1"Hg
The month with the highest atmospheric pressure is January (30.11"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in December
DeKalb, IL
- Average wind speed in December: 9.3mph
The windiest month (with the highest average wind speed) is April (10mph).
The calmest month (with the lowest average wind speed) is August (6.2mph).
Average humidity in December
DeKalb, IL
- Average humidity in December: 83%
The months with the highest relative humidity are January and July (85%).
The months with the lowest relative humidity are April and October (75%).
Average rainfall in December
DeKalb, IL
- Average rainfall in December: 1.69"
The wettest month (with the highest rainfall) is May (4.37").
The driest month (with the least rainfall) is February (1.65").
Average rainfall days in December
DeKalb, IL
- Average rainfall days in December: 8.5 days
The month with the highest number of rainy days is May (18.3 days).
The month with the least rainy days is February (4.7 days).
Average snowfall in December
DeKalb, IL
- Average snowfall in December: 2.91"
The month with the highest snowfall is January (5.55").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
DeKalb, IL
- Average snowfall days in December: 10 days
The month with the highest number of snowfall days is January (11.8 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
DeKalb, IL
- Average daylight in December: 9h and 12min
The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in December: 3h and 54min
The month with the most sunshine is July (Average sunshine: 9h and 36min).
The month with the least sunshine is January (Average sunshine: 3h and 36min).
Average sunshine days in December
DeKalb, IL
- Average sunshine days in December: 15.5 days
The month with the most sunshine days is November (17.2 days).
The months with the least sunshine days are June and July (10.3 days).
Average UV index in December
DeKalb, IL
- Average UV index in December: 1
The months with the highest UV index are June and August (UV index 6).
The months with the lowest UV index are January and December (UV index 1).
Average cloud cover in December
DeKalb, IL
- Average cloud cover in December: 59
The month with the most cloud cover is January (Cloud cover 63).
The months with the least cloud cover are August and September (Cloud cover 35).
Average visibility in December
DeKalb, IL
- Average visibility in December: 6mi
The months with the highest visibility are March, April, May, June, October, November and December (6mi).
The months with the lowest visibility are January, February, July, August and September (5mi).
