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
During the transition into December, Crystal Lake observes a decrease in the average high-temperature, falling from a chilly 44.6°F (7°C) in November to a cold 32.9°F (0.5°C). Throughout the month of December, Crystal Lake sees a steady low-temperature average of 22.8°F (-5.1°C).Humidity
The average relative humidity in December is 82%.Rainfall
November and December are months with the least rain when the rain falls for 7.9 days and typically aggregates up to 0.94" (24mm) of rain.Snowfall
January through May, October through December are months with snowfall. In Crystal Lake, during December, snow falls for 10.9 days and regularly aggregates up to 1.89" (48mm) of snow. Throughout the year, there are 48.7 snowfall days, and 11.85" (301mm) of snow is accumulated.Daylight
December has the shortest days of the year, with an average of 9h and 12min of daylight.On the first day of December, sunrise is at 7:03 am and sunset at 4:22 pm. On the last day of the month, sunrise is at 7:21 am and sunset at 4:31 pm CST.
Sunshine
In Crystal Lake, the average sunshine in December 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 estimate of 2, and below, represents a minimal health vulnerability from unprotected exposure to Sun's UV rays for average individuals.Note: A maximum high UV index of 1 in December translates into the following recommendations:
Prolonged exposure to sunlight rarely troubles the majority, but constant protection is vital for babies, children, and fair-skinned people. Midday is the peak time for the Sun's radiation; stay in the shade and protect yourself. Safeguard your eyes, ears, and face from sun rays with the aid of a wide-brim hat. Be alert to the fact! The reflection from snow can nearly double the UV radiation of the Sun.
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?
What is the driest month?
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?
What time are sunrise and sunset in December?
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
Crystal Lake, IL
- Average high temperature in December: 32.9°F
The warmest month (with the highest average high temperature) is July (79.5°F).
The month with the lowest average high temperature is January (27°F).
- Average low temperature in December: 22.8°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
Crystal Lake, IL
- Average pressure in December: 30.09"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
Crystal Lake, IL
- Average wind speed in December: 9.3mph
The windiest months (with the highest average wind speed) are January and February (9.9mph).
The calmest month (with the lowest average wind speed) is August (6.2mph).
Average humidity in December
Crystal Lake, IL
- Average humidity in December: 82%
The months with the highest relative humidity are January and February (85%).
The months with the lowest relative humidity are April and October (76%).
Average rainfall in December
Crystal Lake, IL
- Average rainfall in December: 0.94"
The wettest month (with the highest rainfall) is June (2.8").
The driest months (with the least rainfall) are November and December (0.94").
Average rainfall days in December
Crystal Lake, IL
- Average rainfall days in December: 7.9 days
The month with the highest number of rainy days is July (18.5 days).
The month with the least rainy days is February (4.8 days).
Average snowfall in December
Crystal Lake, IL
- Average snowfall in December: 1.89"
The month with the highest snowfall is January (3.31").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in December
Crystal Lake, IL
- Average snowfall days in December: 10.9 days
The month with the highest number of snowfall days is January (12.5 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Crystal Lake, 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: 10h and 0min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).
Average sunshine days in December
Crystal Lake, IL
- Average sunshine days in December: 16.2 days
The month with the most sunshine days is November (17.3 days).
The month with the least sunshine days is July (10 days).
Average UV index in December
Crystal Lake, IL
- Average UV index in December: 1
The month with the highest UV index is August (UV index 6).
The months with the lowest UV index are January and December (UV index 1).
Average cloud cover in December
Crystal Lake, IL
- Average cloud cover in December: 59
The month with the most cloud cover is January (Cloud cover 62).
The months with the least cloud cover are July and September (Cloud cover 32).
Average visibility in December
Crystal Lake, IL
- Average visibility in December: 6mi
The months with the highest visibility are March, April, May, June, July, September, October, November and December (6mi).
The months with the lowest visibility are January, February and August (5mi).
Crystal Lake, Illinois, USA
Weather forecast for your location
2. Allow the app to use your location