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
The commencement of December involves a temperature shift, with the average high-temperature dropping from a frosty 45.5°F (7.5°C) in November to a cold 33.8°F (1°C). In December, the nighttime temperature lowers to an average of 23.2°F (-4.9°C).Humidity
In Rock Falls, the average relative humidity in December is 82%.Rainfall
In Rock Falls, during December, the rain falls for 5.7 days and regularly aggregates up to 0.83" (21mm) of precipitation. Throughout the year, in Rock Falls, there are 130.2 rainfall days, and 17.36" (441mm) of precipitation is accumulated.Snowfall
January through April, October through December are months with snowfall. In December, it is snowing for 7.4 days. Throughout December, 1.3" (33mm) of snow is accumulated. Throughout the year, there are 34.2 snowfall days, and 7.87" (200mm) of snow is accumulated.Daylight
December has the shortest days of the year, with an average of 9h and 12min of daylight.On the first day of the month, sunrise is at 7:07 am and sunset at 4:28 pm. On the last day of December, sunrise is at 7:25 am and sunset at 4:38 pm CST.
Sunshine
In December, the average sunshine is 4.1h.UV index
The month with the lowest UV index is December, with an average maximum UV index of 1. A UV Index value of 2, and less, symbolizes a minimal health vulnerability from unprotected exposure to Sun's UV rays for ordinary individuals.Note: In December, a regular UV index of 1 translates into these guidelines:
Apart from children, who require continuous protection, most can endure sun exposure for up to an hour without experiencing burns. Avoiding direct sun during mid-day hours can prevent harmful UV radiation exposure. Equip yourself with UVA and UVB-filtering sunglasses on clear, sunny days. Be alert! Nearly double the UV rays from the Sun can be reflected by snow.
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?
How many days does it rain in December?
How much does it snow in December?
What is the month with the shortest days?
How many hours of daylight does Rock Falls have in December?
When is the sunrise / sunset in December?
How many hours of sunshine does Rock Falls have in December?
What is the month with the lowest UV index?
What is the UV index reading in December?
Average temperature in December
Rock Falls, IL
- Average high temperature in December: 33.8°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 (27.7°F).
- Average low temperature in December: 23.2°F
The month with the highest average low temperature is July (63.9°F).
The coldest month (with the lowest average low temperature) is January (14.9°F).
Average pressure in December
Rock Falls, 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 (29.91"Hg).
Average wind speed in December
Rock Falls, IL
- Average wind speed in December: 9.5mph
The windiest month (with the highest average wind speed) is April (10.4mph).
The calmest month (with the lowest average wind speed) is August (6.4mph).
Average humidity in December
Rock Falls, IL
- Average humidity in December: 82%
The months with the highest relative humidity are January and July (85%).
The month with the lowest relative humidity is October (73%).
Average rainfall in December
Rock Falls, IL
- Average rainfall in December: 0.83"
The wettest month (with the highest rainfall) is May (2.83").
The driest months (with the least rainfall) are January and February (0.75").
Average rainfall days in December
Rock Falls, IL
- Average rainfall days in December: 5.7 days
The month with the highest number of rainy days is May (17.3 days).
The month with the least rainy days is January (4.8 days).
Average snowfall in December
Rock Falls, IL
- Average snowfall in December: 1.3"
The month with the highest snowfall is January (2.56").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in December
Rock Falls, IL
- Average snowfall days in December: 7.4 days
The month with the highest number of snowfall days is January (10.2 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
Rock Falls, IL
- Average daylight in December: 9h and 1min
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: 4h and 1min
The month with the most sunshine is July (Average sunshine: 9h and 48min).
The month with the least sunshine is January (Average sunshine: 3h and 48min).
Average sunshine days in December
Rock Falls, IL
- Average sunshine days in December: 18.8 days
The months with the most sunshine days are November and December (18.8 days).
The month with the least sunshine days is June (11.3 days).
Average UV index in December
Rock Falls, IL
- Average UV index in December: 1
The month with the highest UV index is July (UV index 6).
The month with the lowest UV index is December (UV index 1).
Average cloud cover in December
Rock Falls, IL
- Average cloud cover in December: 57
The month with the most cloud cover is January (Cloud cover 60).
The month with the least cloud cover is September (Cloud cover 31).
Average visibility in December
Rock Falls, 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).
Rock Falls, Illinois, USA
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