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 arrival, McLean's weather changes as the average high-temperature falls from a chilly 49.1°F (9.5°C) in November to a wintry 37.4°F (3°C). Throughout the month of December, McLean observes an average nighttime temperature of 27°F (-2.8°C).Humidity
In McLean, the average relative humidity in December is 79%.Rainfall
December is the month with the least rainfall. Rain falls for 7.2 days and accumulates 0.87" (22mm) of precipitation.Snowfall
Months with snowfall are January through April, November and December. In McLean, during December, snow falls for 5.3 days and regularly aggregates up to 0.91" (23mm) of snow. In McLean, during the entire year, snow falls for 27.1 days and aggregates up to 7.2" (183mm) of snow.Daylight
The month with the shortest days is December, with an average of 9h and 24min of daylight.On the first day of December, sunrise is at 7:00 am and sunset at 4:31 pm. On the last day of the month, sunrise is at 7:19 am and sunset at 4:40 pm CST.
Sunshine
In December, the average sunshine in McLean 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 minimal health hazard from unprotected exposure to Sun's UV rays for the average person.Note: In December, a daily maximum UV index of 2 leads to the following instructions:
Extended sunlight exposure does not pose significant problems for most people, except for children, infants, and people with fair skin who always need shielding. The Sun's UV radiation is especially harmful around midday, so reduce exposure and stay safe. Fend off the sun's harsh rays with appropriate clothing, a wide-brim hat, and UV-protective sunglasses. Take careful note! The UV radiation of the Sun can be nearly doubled by snow reflection.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How cold is it in McLean in December?
What is the average humidity in December in McLean?
What is the driest month in McLean?
How many days does it rain in December in McLean?
How much does it snow in McLean in December?
What is the month with the shortest days in McLean?
What is the average length of the day in December in McLean?
When are sunrise and sunset in December in McLean?
How many hours of sunshine does McLean have in December?
What is the month with the lowest UV index in McLean?
How high is the UV index in December in McLean?
Average temperature in December
McLean, IL
- Average high temperature in December: 37.4°F
The warmest month (with the highest average high temperature) is July (81.5°F).
The month with the lowest average high temperature is January (31.6°F).
- Average low temperature in December: 27°F
The month with the highest average low temperature is July (65.1°F).
The coldest month (with the lowest average low temperature) is January (19.8°F).
Average pressure in December
McLean, IL
- Average pressure in December: 30.12"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in December
McLean, IL
- Average wind speed in December: 9.9mph
The windiest month (with the highest average wind speed) is April (10.6mph).
The calmest month (with the lowest average wind speed) is August (6.3mph).
Average humidity in December
McLean, IL
- Average humidity in December: 79%
The month with the highest relative humidity is July (85%).
The month with the lowest relative humidity is October (70%).
Average rainfall in December
McLean, IL
- Average rainfall in December: 0.87"
The wettest month (with the highest rainfall) is May (2.2").
The driest month (with the least rainfall) is December (0.87").
Average rainfall days in December
McLean, IL
- Average rainfall days in December: 7.2 days
The month with the highest number of rainy days is May (16.5 days).
The month with the least rainy days is February (5.9 days).
Average snowfall in December
McLean, IL
- Average snowfall in December: 0.91"
The month with the highest snowfall is January (2.2").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
McLean, IL
- Average snowfall days in December: 5.3 days
The month with the highest number of snowfall days is January (9.5 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
McLean, IL
- Average daylight in December: 9h and 2min
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 24min).
- Average sunshine in December: 4h and 3min
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 0min).
Average sunshine days in December
McLean, IL
- Average sunshine days in December: 20 days
The months with the most sunshine days are November and December (20 days).
The month with the least sunshine days is May (11.6 days).
Average UV index in December
McLean, 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
McLean, IL
- Average cloud cover in December: 53
The month with the most cloud cover is January (Cloud cover 57).
The month with the least cloud cover is September (Cloud cover 30).
Average visibility in December
McLean, 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).
McLean, Illinois, USA
Weather forecast for your location
2. Allow the app to use your location