December weather forecastMarietta, IL
December
Weather in December
The first month of the winter, December, is also a wintry month in Marietta, Illinois, with temperature in the range of an average low of 26.4°F (-3.1°C) and an average high of 37°F (2.8°C).Temperature
Marietta's December weather shows a moderate shift in high-temperatures, falling from November's chilly 49.1°F (9.5°C) to a cold 37°F (2.8°C). An average low-temperature of 26.4°F (-3.1°C) marks the month of December.Humidity
In Marietta, the average relative humidity in December is 79%.Rainfall
The month with the least rainfall in Marietta is December, when the rain falls for 6.5 days and typically collects 0.94" (24mm) of precipitation.Snowfall
January through April, October through December are months with snowfall. In Marietta, Illinois, in December, during 5 snowfall days, 1.1" (28mm) of snow is typically accumulated. In Marietta, during the entire year, snow falls for 27.4 days and aggregates up to 9.21" (234mm) 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 the month, sunrise is at 7:06 am and sunset at 4:35 pm. On the last day of December, sunrise is at 7:24 am and sunset at 4:45 pm CST.
Sunshine
In December, the average sunshine in Marietta is 4.5h.UV index
January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index of 2, and less, symbolizes a low threat to health from unprotected exposure to Sun's UV rays for the average person.Note: A maximum daily UV index of 2 during December morphs into the following directions:
Prolonged exposure to sunlight rarely troubles the majority, but constant protection is vital for babies, children, and fair-skinned people. Considering the harmful UV rays from the Sun during midday, it's essential to reduce exposure. Arm yourself against UV rays' harm with protective apparel and UV-filtering shades. Take to heart! Snow reflection can almost magnify the Sun's UV radiation twofold.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Marietta, IL
- Average high temperature in December: 37°F
The warmest month (with the highest average high temperature) is July (82.8°F).
The month with the lowest average high temperature is January (31.5°F).
- Average low temperature in December: 26.4°F
The month with the highest average low temperature is July (65.8°F).
The coldest month (with the lowest average low temperature) is January (19.4°F).
Average pressure in December
Marietta, 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
Marietta, IL
- Average wind speed in December: 9.8mph
The windiest month (with the highest average wind speed) is April (10.4mph).
The calmest months (with the lowest average wind speed) are July and August (6.5mph).
Average humidity in December
Marietta, IL
- Average humidity in December: 79%
The month with the highest relative humidity is July (83%).
The month with the lowest relative humidity is October (71%).
Average rainfall in December
Marietta, IL
- Average rainfall in December: 0.94"
The wettest month (with the highest rainfall) is May (3.23").
The driest month (with the least rainfall) is December (0.94").
Average rainfall days in December
Marietta, IL
- Average rainfall days in December: 6.5 days
The month with the highest number of rainy days is May (16.7 days).
The month with the least rainy days is February (4.7 days).
Average snowfall in December
Marietta, IL
- Average snowfall in December: 1.1"
The month with the highest snowfall is January (3.35").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in December
Marietta, IL
- Average snowfall days in December: 5 days
The month with the highest number of snowfall days is January (9.4 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
Marietta, IL
- Average daylight in December: 9h and 18min
The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 18min).
- Average sunshine in December: 4h and 30min
The months with the most sunshine are June and July (Average sunshine: 10h and 6min).
The month with the least sunshine is January (Average sunshine: 4h and 6min).
Average sunshine days in December
Marietta, IL
- Average sunshine days in December: 20.4 days
The month with the most sunshine days is December (20.4 days).
The month with the least sunshine days is June (11.1 days).
Average UV index in December
Marietta, 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
Marietta, IL
- Average cloud cover in December: 52
The month with the most cloud cover is January (Cloud cover 56).
The month with the least cloud cover is September (Cloud cover 29).
Average visibility in December
Marietta, 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).
