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
The arrival of December indicates a decrease in the average high-temperature, moving from a frosty 46.9°F (8.3°C) in November to a cold 34.5°F (1.4°C). Port Byron witnesses an average low-temperature of 23.9°F (-4.5°C) throughout the month of December.Humidity
The average relative humidity in December is 81%.Rainfall
December is the month with the least rainfall. Rain falls for 4.1 days and accumulates 0.35" (9mm) of precipitation.Snowfall
Months with snowfall are January through April, September through December. In Port Byron, in December, during 5 snowfall days, 0.39" (10mm) of snow is typically accumulated. Throughout the year, there are 24.5 snowfall days, and 4.09" (104mm) 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 December, sunrise is at 7:09 am and sunset at 4:31 pm. On the last day of the month, sunrise is at 7:27 am and sunset at 4:41 pm CST.
Sunshine
In December, the average sunshine is 4.2h.UV index
In December, the average daily maximum UV index is 2. A UV Index reading of 2, and below, represents a low health risk from exposure to the Sun's UV rays for the average person.Note: The maximum UV index, 2 during December, leads to the following recommendations:
While most people are not greatly affected by extended sun exposure, those with fair skin, babies, and children must always have protection. Direct exposure to the Sun's intense radiation around midday should be avoided for health reasons. By wearing a generously brimmed hat, you can cut UV radiation exposure significantly. Notice! The UV radiation of the Sun can be intensified nearly twofold due to the reflective quality of snow.
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?
What is the driest month?
How many days does it rain in December?
How much does it snow in December?
What is the month with the shortest days in Port Byron?
What is the average length of the day in December?
When is the sunrise / sunset in December?
How long on average sun shines in December?
What is the UV index reading in December?
Average temperature in December
Port Byron, IL
- Average high temperature in December: 34.5°F
The warmest month (with the highest average high temperature) is July (81.7°F).
The month with the lowest average high temperature is January (28.2°F).
- Average low temperature in December: 23.9°F
The month with the highest average low temperature is July (64.8°F).
The coldest month (with the lowest average low temperature) is January (15.4°F).
Average pressure in December
Port Byron, IL
- Average pressure in December: 30.11"Hg
The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).
Average wind speed in December
Port Byron, IL
- Average wind speed in December: 9.8mph
The windiest month (with the highest average wind speed) is April (10.6mph).
The calmest month (with the lowest average wind speed) is August (6.7mph).
Average humidity in December
Port Byron, IL
- Average humidity in December: 81%
The months with the highest relative humidity are January and July (83%).
The month with the lowest relative humidity is October (71%).
Average rainfall in December
Port Byron, IL
- Average rainfall in December: 0.35"
The wettest month (with the highest rainfall) is May (1.61").
The driest month (with the least rainfall) is December (0.35").
Average rainfall days in December
Port Byron, IL
- Average rainfall days in December: 4.1 days
The month with the highest number of rainy days is May (13.4 days).
The month with the least rainy days is January (3.2 days).
Average snowfall in December
Port Byron, IL
- Average snowfall in December: 0.39"
The month with the highest snowfall is January (1.26").
The months with the least snowfall are May, June, July and August (0").
Average snowfall days in December
Port Byron, IL
- Average snowfall days in December: 5 days
The month with the highest number of snowfall days is January (7.2 days).
The months with the least snowfall days are May, June, July and August (0 days).
Average daylight in December /
Average sunshine in December
Port Byron, IL
- Average daylight in December: 9h and 1min
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 12min).
- Average sunshine in December: 4h and 1min
The month with the most sunshine is July (Average sunshine: 10h and 6min).
The month with the least sunshine is January (Average sunshine: 3h and 54min).
Average sunshine days in December
Port Byron, IL
- Average sunshine days in December: 22.4 days
The month with the most sunshine days is December (22.4 days).
The month with the least sunshine days is June (14.4 days).
Average UV index in December
Port Byron, IL
- Average UV index in December: 2
The month with the highest UV index is July (UV index 6).
The month with the lowest UV index is January (UV index 1).
Average cloud cover in December
Port Byron, IL
- Average cloud cover in December: 56
The month with the most cloud cover is January (Cloud cover 58).
The month with the least cloud cover is August (Cloud cover 30).
Average visibility in December
Port Byron, 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).
Port Byron, Illinois, USA
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