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's onset brings a slight change in high-temperatures, falling from a frosty 46.6°F (8.1°C) in November to a cold 34.7°F (1.5°C). Throughout December, the nighttime temperature averages to a freezing cold 24.6°F (-4.1°C).Humidity
In December, the average relative humidity is 81%.Rainfall
December is the month with the least rainfall. Rain falls for 7.1 days and accumulates 1.06" (27mm) of precipitation.Snowfall
Months with snowfall are January through May, October through December. In Romeoville, in December, snow falls for 9.7 days, with typically accumulated 1.89" (48mm) of snow. In Romeoville, during the entire year, snow falls for 44.4 days and aggregates up to 11.93" (303mm) 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 4:22 pm. On the last day of the month, sunrise is at 7:19 am and sunset at 4:32 pm CST.
Sunshine
In Romeoville, Illinois, the average sunshine in December is 4.1h.UV index
With an average maximum UV index of 1, December is the month 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 average individuals.Note: A daily maximum UV index of 1 in December translates into the following instructions:
Protection from prolonged sun exposure is necessary for babies, children, and individuals with sensitive skin. The most potent solar radiation is around mid-day, so one should minimize exposure to direct sunlight during this period. To mitigate harm from sun exposure, pick sunglasses offering UVA and UVB defense. Be cautious! The UV radiation from the Sun can be magnified almost twofold by snow reflection.
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 much does it rain in December?
How many days 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 Romeoville have in December?
What is the month with the lowest UV index?
What is the UV index intensity in December in Romeoville?
Average temperature in December
Romeoville, IL
- Average high temperature in December: 34.7°F
The warmest month (with the highest average high temperature) is July (81.9°F).
The month with the lowest average high temperature is January (28.8°F).
- Average low temperature in December: 24.6°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 (17.1°F).
Average pressure in December
Romeoville, 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
Romeoville, IL
- Average wind speed in December: 9mph
The windiest month (with the highest average wind speed) is January (9.7mph).
The calmest month (with the lowest average wind speed) is August (6mph).
Average humidity in December
Romeoville, IL
- Average humidity in December: 81%
The months with the highest relative humidity are January and February (83%).
The month with the lowest relative humidity is October (73%).
Average rainfall in December
Romeoville, IL
- Average rainfall in December: 1.06"
The wettest month (with the highest rainfall) is May (2.83").
The driest month (with the least rainfall) is December (1.06").
Average rainfall days in December
Romeoville, IL
- Average rainfall days in December: 7.1 days
The month with the highest number of rainy days is July (18.1 days).
The month with the least rainy days is February (4.9 days).
Average snowfall in December
Romeoville, IL
- Average snowfall in December: 1.89"
The month with the highest snowfall is January (3.11").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
Romeoville, IL
- Average snowfall days in December: 9.7 days
The month with the highest number of snowfall days is January (12.1 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Romeoville, IL
- Average daylight in December: 9h and 1min
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 1min
The months with the most sunshine are July and August (Average sunshine: 9h and 54min).
The month with the least sunshine is January (Average sunshine: 3h and 48min).
Average sunshine days in December
Romeoville, IL
- Average sunshine days in December: 16.2 days
The month with the most sunshine days is November (18.4 days).
The month with the least sunshine days is July (9.3 days).
Average UV index in December
Romeoville, IL
- Average UV index in December: 1
The months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is December (UV index 1).
Average cloud cover in December
Romeoville, IL
- Average cloud cover in December: 58
The month with the most cloud cover is January (Cloud cover 60).
The month with the least cloud cover is August (Cloud cover 31).
Average visibility in December
Romeoville, IL
- Average visibility in December: 6mi
The months with the highest visibility are March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January and February (5mi).
Romeoville, Illinois, USA
Weather forecast for your location
2. Allow the app to use your location