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
Observing a mild shift, the average high-temperature during December reduces from November's chilly 47.5°F (8.6°C) to an icy 35.4°F (1.9°C). During December, the nighttime temperature in Rio averages to a subzero cold 24.6°F (-4.1°C).Humidity
In Rio, the average relative humidity in December is 81%.Rainfall
January and December are months with the least rain in Rio when the rain falls for 4.5 days and typically aggregates up to 0.47" (12mm) of rain.Snowfall
Months with snowfall are January through April, October through December. In Rio, in December, during 6 snowfall days, 0.43" (11mm) of snow is typically accumulated. In Rio, Illinois, during the entire year, snow falls for 28 days and aggregates up to 4.53" (115mm) of snow.Daylight
December has the shortest days of the year, with an average of 9h and 18min of daylight.On the first day of December, sunrise is at 7:08 am and sunset at 4:33 pm. On the last day of the month, sunrise is at 7:26 am and sunset at 4:43 pm CST.
Sunshine
In December, the average sunshine is 4.4h.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 low threat to health from unprotected exposure to Sun's UV rays for average individuals.Note: An average maximum UV index of 1 in December leads to these recommendations:
Although the majority can endure up to an hour in the sun without burns, children always require sun protection. It's crucial to reduce time in the direct Sun around mid-day due to the intense solar radiation. Counter UV radiation's ill effects with clothing designed for sun safety and UV-resistant eyewear. Mind you! Snow reflection can increase the intensity of the Sun's UV radiation nearly twofold.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How cold is it in Rio in December?
What is the average humidity in December in Rio?
What is the driest month in Rio?
How many days does it rain in December in Rio?
How much does it snow in Rio in December?
What is the month with the shortest days in Rio?
What is the average length of the day in December in Rio?
When is the sunrise / sunset in December in Rio?
How many hours of sunshine does Rio have in December?
What is the month with the lowest UV index in Rio?
How high is the UV index in December in Rio?
Average temperature in December
Rio, IL
- Average high temperature in December: 35.4°F
The warmest month (with the highest average high temperature) is July (81.1°F).
The month with the lowest average high temperature is January (29.5°F).
- Average low temperature in December: 24.6°F
The month with the highest average low temperature is July (64.9°F).
The coldest month (with the lowest average low temperature) is January (17.4°F).
Average pressure in December
Rio, IL
- Average pressure in December: 30.11"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).
Average wind speed in December
Rio, IL
- Average wind speed in December: 9.9mph
The windiest month (with the highest average wind speed) is April (10.8mph).
The calmest months (with the lowest average wind speed) are July and August (6.8mph).
Average humidity in December
Rio, IL
- Average humidity in December: 81%
The month with the highest relative humidity is July (84%).
The month with the lowest relative humidity is October (72%).
Average rainfall in December
Rio, IL
- Average rainfall in December: 0.47"
The wettest month (with the highest rainfall) is May (1.65").
The driest months (with the least rainfall) are January and December (0.47").
Average rainfall days in December
Rio, IL
- Average rainfall days in December: 4.5 days
The month with the highest number of rainy days is May (15.2 days).
The month with the least rainy days is February (3.9 days).
Average snowfall in December
Rio, IL
- Average snowfall in December: 0.43"
The month with the highest snowfall is January (1.38").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in December
Rio, IL
- Average snowfall days in December: 6 days
The month with the highest number of snowfall days is January (8.8 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
Rio, IL
- Average daylight in December: 9h and 2min
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 18min).
- Average sunshine in December: 4h and 2min
The month with the most sunshine is June (Average sunshine: 10h and 6min).
The month with the least sunshine is January (Average sunshine: 4h and 0min).
Average sunshine days in December
Rio, IL
- Average sunshine days in December: 21.6 days
The month with the most sunshine days is December (21.6 days).
The month with the least sunshine days is June (12.4 days).
Average UV index in December
Rio, IL
- Average UV index in December: 1
The months with the highest UV index are June and July (UV index 6).
The month with the lowest UV index is December (UV index 1).
Average cloud cover in December
Rio, IL
- Average cloud cover in December: 54
The month with the most cloud cover is January (Cloud cover 58).
The month with the least cloud cover is September (Cloud cover 30).
Average visibility in December
Rio, IL
- Average visibility in December: 6mi
The months with the highest visibility are January, February, March, April, May, June, August, September, October, November and December (6mi).
The month with the lowest visibility is July (5mi).
Rio, Illinois, USA
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