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
December comes with a decrease in the average high-temperature, falling from a chilly 45.3°F (7.4°C) in November to an icy 33.1°F (0.6°C). Cortland temperatures generally rest at a low of 23°F (-5°C) during the December nights.Humidity
In Cortland, the average relative humidity in December is 83%.Rainfall
In December, the rain falls for 8.5 days. Throughout December, 1.69" (43mm) of precipitation is accumulated. In Cortland, during the entire year, the rain falls for 152.6 days and collects up to 32.09" (815mm) of precipitation.Snowfall
January through May, October through December are months with snowfall. In Cortland, Illinois, during December, snow falls for 10 days and regularly aggregates up to 2.91" (74mm) of snow. Throughout the year, there are 44.3 snowfall days, and 17.87" (454mm) of snow is accumulated.Daylight
The month with the shortest days is December, with an average of 9h and 12min of daylight.On the first day of the month, sunrise is at 7:03 am and sunset at 4:24 pm. On the last day of December, sunrise is at 7:22 am and sunset at 4:33 pm CST.
Sunshine
In December, the average sunshine is 3.9h.UV index
January and December, with an average maximum UV index of 1, are months with the lowest UV index. A UV Index reading of 2, and below, represents a minimal health vulnerability from unprotected exposure to Sun's UV rays for average individuals.Note: The average daily UV index of 1 in December transforms into the following instructions:
Although prolonged sun exposure does not typically bother most people, children, babies, and those with sensitive skin should always have protection. Being in direct Sun during midday can be harmful due to intense solar radiation; take precautions. On sunny days, it's ideal to wear sunglasses that filter out UVA and UVB rays. Caution! The reflection of snow can nearly double the intensity of the Sun's UV radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How cold is December?
What is the average humidity in December?
How many days does it rain in December?
How many days does it snow in December?
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 in Cortland?
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
Cortland, IL
- Average high temperature in December: 33.1°F
The warmest month (with the highest average high temperature) is July (80.2°F).
The month with the lowest average high temperature is January (27°F).
- Average low temperature in December: 23°F
The month with the highest average low temperature is July (63.1°F).
The coldest month (with the lowest average low temperature) is January (15.1°F).
Average pressure in December
Cortland, IL
- Average pressure in December: 30.1"Hg
The month with the highest atmospheric pressure is January (30.11"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in December
Cortland, IL
- Average wind speed in December: 9.3mph
The windiest month (with the highest average wind speed) is April (10mph).
The calmest month (with the lowest average wind speed) is August (6.2mph).
Average humidity in December
Cortland, IL
- Average humidity in December: 83%
The months with the highest relative humidity are January and July (85%).
The months with the lowest relative humidity are April and October (75%).
Average rainfall in December
Cortland, IL
- Average rainfall in December: 1.69"
The wettest month (with the highest rainfall) is May (4.37").
The driest month (with the least rainfall) is February (1.65").
Average rainfall days in December
Cortland, IL
- Average rainfall days in December: 8.5 days
The month with the highest number of rainy days is May (18.3 days).
The month with the least rainy days is February (4.7 days).
Average snowfall in December
Cortland, IL
- Average snowfall in December: 2.91"
The month with the highest snowfall is January (5.55").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
Cortland, IL
- Average snowfall days in December: 10 days
The month with the highest number of snowfall days is January (11.8 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Cortland, IL
- Average daylight in December: 9h and 1min
The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in December: 3h and 5min
The month with the most sunshine is July (Average sunshine: 9h and 36min).
The month with the least sunshine is January (Average sunshine: 3h and 36min).
Average sunshine days in December
Cortland, IL
- Average sunshine days in December: 15.5 days
The month with the most sunshine days is November (17.2 days).
The months with the least sunshine days are June and July (10.3 days).
Average UV index in December
Cortland, IL
- Average UV index in December: 1
The months with the highest UV index are June and August (UV index 6).
The months with the lowest UV index are January and December (UV index 1).
Average cloud cover in December
Cortland, IL
- Average cloud cover in December: 59
The month with the most cloud cover is January (Cloud cover 63).
The months with the least cloud cover are August and September (Cloud cover 35).
Average visibility in December
Cortland, IL
- Average visibility in December: 6mi
The months with the highest visibility are March, April, May, June, October, November and December (6mi).
The months with the lowest visibility are January, February, July, August and September (5mi).
Cortland, Illinois, USA
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