December weather forecastJoliet, IL
December
Weather in December
December witnesses the advent of winter once more, closing the year with the second-highest snowfall estimated at 2.4" (61mm). The month’s average high caps at 35.1°F (1.7°C), reinforcing the frosty atmosphere of Joliet winters. Its freezing temperatures are accompanied by limited sunlight and extended nights. The wind retains its chilly sting and humidity remains high, ensuring a substantial likelihood of foggy mornings and evenings.Temperature
As December arrives, Joliet's weather displays a decrease in high-temperatures, transitioning from November's chilly 47.1°F (8.4°C) to a cold 35.1°F (1.7°C). December nights are marked by an average temperature drop to a freezing cold 25°F (-3.9°C).Humidity
In Joliet, the average relative humidity in December is 82%.Rainfall
In Joliet, in December, during 8.1 rainfall days, 1.69" (43mm) of precipitation is typically accumulated. In Joliet, during the entire year, the rain falls for 153.6 days and collects up to 32.72" (831mm) of precipitation.Snowfall
Months with snowfall are January through April, November and December. In Joliet, in December, snow falls for 8 days, with typically accumulated 2.4" (61mm) of snow. In Joliet, during the entire year, snow falls for 38.2 days and aggregates up to 14.61" (371mm) of snow.Daylight
The month with the shortest days is December, with an average of 9h and 12min of daylight.On the first day of December, sunrise is at 7:00 am and sunset at 4:23 pm. On the last day of the month, sunrise is at 7:18 am and sunset at 4:32 pm CST.
Sunshine
The average sunshine in December is 4.1h.UV index
January and December, with an average maximum UV index of 1, are months with the lowest UV index in Joliet. A UV Index of 2, and less, symbolizes a low health risk from unprotected exposure to Sun's UV rays for average individuals.Note: An average UV index of 1 in December transforms into this advice:
While most people can stay under the sun for an hour without burning, children must always be guarded against sun exposure. The Sun's harshest UV rays are around midday; it's wise to seek shade and limit time outdoors. Wearing a wide-brim hat can block approximately 50% of UV radiation, protecting the eyes. Note well! The intensity of the Sun's UV rays can be nearly doubled by snow reflection.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Joliet, IL
- Average high temperature in December: 35.1°F
The warmest month (with the highest average high temperature) is July (81.3°F).
The month with the lowest average high temperature is January (29.3°F).
- Average low temperature in December: 25°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 (17.4°F).
Average pressure in December
Joliet, IL
- Average pressure in December: 30.1"Hg
The month with the highest atmospheric pressure is January (30.12"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in December
Joliet, IL
- Average wind speed in December: 8.9mph
The windiest month (with the highest average wind speed) is April (9.7mph).
The calmest month (with the lowest average wind speed) is August (5.9mph).
Average humidity in December
Joliet, IL
- Average humidity in December: 82%
The month with the highest relative humidity is February (83%).
The month with the lowest relative humidity is October (73%).
Average rainfall in December
Joliet, IL
- Average rainfall in December: 1.69"
The wettest month (with the highest rainfall) is May (4.41").
The driest month (with the least rainfall) is February (1.61").
Average rainfall days in December
Joliet, IL
- Average rainfall days in December: 8.1 days
The month with the highest number of rainy days is July (17.9 days).
The month with the least rainy days is February (5.7 days).
Average snowfall in December
Joliet, IL
- Average snowfall in December: 2.4"
The month with the highest snowfall is January (4.33").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
Joliet, IL
- Average snowfall days in December: 8 days
The month with the highest number of snowfall days is January (11.9 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
Joliet, 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 6min
The month with the most sunshine is August (Average sunshine: 9h and 42min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).
Average sunshine days in December
Joliet, IL
- Average sunshine days in December: 15.9 days
The month with the most sunshine days is November (18.1 days).
The month with the least sunshine days is June (10.4 days).
Average UV index in December
Joliet, IL
- Average UV index in December: 1
The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January and December (UV index 1).
Average cloud cover in December
Joliet, IL
- Average cloud cover in December: 58
The month with the most cloud cover is January (Cloud cover 60).
The months with the least cloud cover are August and September (Cloud cover 34).
Average visibility in December
Joliet, IL
- Average visibility in December: 6mi
The months with the highest visibility are March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are January, February, July and August (5mi).
