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
Stepping into December, Irwin observes a temperature decline, with the average high falling from November's chilly 47.5°F (8.6°C) to a wintry 36.3°F (2.4°C). December in Irwin generally records an average low-temperature of 26.1°F (-3.3°C).Humidity
In Irwin, the average relative humidity in December is 81%.Rainfall
In December, the rain falls for 7.3 days. Throughout December, 1.14" (29mm) of precipitation is accumulated. In Irwin, during the entire year, the rain falls for 142.1 days and collects up to 22.56" (573mm) of precipitation.Snowfall
Months with snowfall are January through April, October through December. In Irwin, during December, snow falls for 8.5 days and regularly aggregates up to 1.54" (39mm) of snow. Throughout the year, there are 39 snowfall days, and 9.02" (229mm) of snow is accumulated.Daylight
The month with the shortest days is December, with an average of 9h and 18min of daylight.On the first day of the month, sunrise is at 6:58 am and sunset at 4:24 pm. On the last day of December, sunrise is at 7:16 am and sunset at 4:33 pm CST.
Sunshine
In December, the average sunshine in Irwin is 4.3h.UV index
January and December, with an average maximum UV index of 1, are months with the lowest UV index. A UV Index of 2, and less, symbolizes a low threat to health from exposure to the Sun's UV radiation for the average person.Note: The maximum UV index of 1 during December translates into these guidelines:
The majority are not significantly affected by prolonged sun exposure. Infants, children, and those with fair skin must always have protection. The Sun's most harmful UV rays are emitted around midday; avoid staying outdoors for long during this time. Your best bet for sun defense on the face, eyes, and neck is a hat with a wide brim. Be aware! The reflective nature of snow can magnify the Sun's UV radiation almost twofold.
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 in Irwin?
How much does it rain in Irwin in December?
How many days does it snow in December in Irwin?
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 long on average sun shines in December?
What is the month with the lowest UV index?
How high is the UV index in December?
Average temperature in December
Irwin, IL
- Average high temperature in December: 36.3°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 (30°F).
- Average low temperature in December: 26.1°F
The month with the highest average low temperature is July (64.2°F).
The coldest month (with the lowest average low temperature) is January (18.3°F).
Average pressure in December
Irwin, IL
- Average pressure in December: 30.11"Hg
The month with the highest atmospheric pressure is January (30.12"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in December
Irwin, IL
- Average wind speed in December: 9.6mph
The windiest months (with the highest average wind speed) are January and April (10.2mph).
The calmest month (with the lowest average wind speed) is August (6.2mph).
Average humidity in December
Irwin, IL
- Average humidity in December: 81%
The month with the highest relative humidity is July (85%).
The month with the lowest relative humidity is October (72%).
Average rainfall in December
Irwin, IL
- Average rainfall in December: 1.14"
The wettest month (with the highest rainfall) is May (3.27").
The driest month (with the least rainfall) is February (1.06").
Average rainfall days in December
Irwin, IL
- Average rainfall days in December: 7.3 days
The month with the highest number of rainy days is May (17.8 days).
The month with the least rainy days is February (5 days).
Average snowfall in December
Irwin, IL
- Average snowfall in December: 1.54"
The month with the highest snowfall is January (2.17").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in December
Irwin, IL
- Average snowfall days in December: 8.5 days
The month with the highest number of snowfall days is January (11.7 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
Irwin, 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 months with the most sunshine are June and July (Average sunshine: 9h and 42min).
The month with the least sunshine is January (Average sunshine: 3h and 48min).
Average sunshine days in December
Irwin, IL
- Average sunshine days in December: 16.8 days
The month with the most sunshine days is November (18.7 days).
The month with the least sunshine days is July (9.3 days).
Average UV index in December
Irwin, IL
- Average UV index in December: 1
The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January and December (UV index 1).
Average cloud cover in December
Irwin, IL
- Average cloud cover in December: 57
The month with the most cloud cover is January (Cloud cover 60).
The months with the least cloud cover are August and September (Cloud cover 34).
Average visibility in December
Irwin, 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).
Irwin, Illinois, USA
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