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
With December's onset, the average high-temperature recedes from November's fresh 51.4°F (10.8°C) to a cold 41.2°F (5.1°C). Flat Rock records a steady low-temperature average of 29.8°F (-1.2°C) during December.Humidity
The average relative humidity in December is 80%.Rainfall
In Flat Rock, in December, during 10.1 rainfall days, 2.91" (74mm) of precipitation is typically accumulated. Throughout the year, in Flat Rock, there are 162.4 rainfall days, and 36.85" (936mm) of precipitation is accumulated.Snowfall
January through April, November and December are months with snowfall. In Flat Rock, in December, during 4.7 snowfall days, 1.85" (47mm) of snow is typically accumulated. Throughout the year, there are 22 snowfall days, and 7.64" (194mm) of snow is accumulated.Daylight
December has the shortest days of the year, with an average of 9h and 30min of daylight.On the first day of the month, sunrise is at 6:50 am and sunset at 4:29 pm. On the last day of December, in Flat Rock, sunrise is at 7:09 am and sunset at 4:38 pm CST.
Sunshine
In Flat Rock, the average sunshine in December is 4.4h.UV index
The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 2. A UV Index of 2, and less, symbolizes a low threat to health from exposure to the Sun's UV radiation for the ordinary person.Note: In December, the average maximum UV index of 2 translates into the following recommendations:
Those with sensitive skin, infants, and children require constant safeguarding from prolonged sun exposure. The Sun's UV radiation is especially harmful around midday, so reduce exposure and stay safe. To cut down UV radiation exposure by about half, sport a wide-brim hat. 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 much does it rain in December?
How many days does it snow in December?
What is the month with the shortest days?
How many hours of daylight does Flat Rock have in December?
What time are sunrise and sunset in December?
How long on average sun shines in December?
What is the month with the lowest UV index?
What is the UV index intensity in December?
Average temperature in December
Flat Rock, IL
- Average high temperature in December: 41.2°F
The warmest month (with the highest average high temperature) is July (83.8°F).
The month with the lowest average high temperature is January (36.1°F).
- Average low temperature in December: 29.8°F
The month with the highest average low temperature is July (66.9°F).
The coldest month (with the lowest average low temperature) is January (23.4°F).
Average pressure in December
Flat Rock, IL
- Average pressure in December: 30.13"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed in December
Flat Rock, IL
- Average wind speed in December: 9.1mph
The windiest months (with the highest average wind speed) are January and February (10mph).
The calmest months (with the lowest average wind speed) are July and August (5.9mph).
Average humidity in December
Flat Rock, IL
- Average humidity in December: 80%
The month with the highest relative humidity is July (81%).
The month with the lowest relative humidity is October (71%).
Average rainfall in December
Flat Rock, IL
- Average rainfall in December: 2.91"
The wettest month (with the highest rainfall) is April (5.2").
The driest month (with the least rainfall) is September (1.89").
Average rainfall days in December
Flat Rock, IL
- Average rainfall days in December: 10.1 days
The month with the highest number of rainy days is May (19.8 days).
The month with the least rainy days is January (8.4 days).
Average snowfall in December
Flat Rock, IL
- Average snowfall in December: 1.85"
The month with the highest snowfall is January (2.32").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
Flat Rock, IL
- Average snowfall days in December: 4.7 days
The month with the highest number of snowfall days is January (6.8 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in December /
Average sunshine in December
Flat Rock, IL
- Average daylight in December: 9h and 3min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 30min).
- Average sunshine in December: 4h and 2min
The month with the most sunshine is June (Average sunshine: 10h and 18min).
The month with the least sunshine is January (Average sunshine: 4h and 12min).
Average sunshine days in December
Flat Rock, IL
- Average sunshine days in December: 16.5 days
The month with the most sunshine days is November (18 days).
The month with the least sunshine days is May (9.7 days).
Average UV index in December
Flat Rock, IL
- Average UV index in December: 2
The months with the highest UV index are June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in December
Flat Rock, IL
- Average cloud cover in December: 53
The month with the most cloud cover is January (Cloud cover 55).
The month with the least cloud cover is August (Cloud cover 29).
Average visibility in December
Flat Rock, IL
- Average visibility in December: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Flat Rock, Illinois, USA
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