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, Alton's weather changes as the average high-temperature falls from a cool 52.2°F (11.2°C) in November to a wintry 41.2°F (5.1°C). Alton experiences a nighttime temperature average of 29.5°F (-1.4°C) during December.Humidity
In December, the average relative humidity is 77%.Rainfall
In Alton, during December, the rain falls for 6.3 days and regularly aggregates up to 0.94" (24mm) of precipitation. In Alton, during the entire year, the rain falls for 128.3 days and collects up to 18.9" (480mm) of precipitation.Snowfall
Months with snowfall in Alton are January through March, November and December. In December, in Alton, Illinois, it is snowing for 3.6 days. Throughout December, 0.55" (14mm) of snow is accumulated. Throughout the year, in Alton, Illinois, there are 17.9 snowfall days, and 3.58" (91mm) of snow is accumulated.Daylight
December has the shortest days of the year in Alton, Illinois, with an average of 9h and 30min of daylight.On the first day of the month, sunrise is at 7:00 am and sunset at 4:39 pm. On the last day of December, sunrise is at 7:19 am and sunset at 4:48 pm CST.
Sunshine
In December, the average sunshine is 4.9h.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 reading of 2, and below, represents a low health risk from exposure to the Sun's UV radiation for the average person.Note: The maximum daily UV index of 2 in December converts into the following recommendations:
People with sensitive skin, children, and babies should always be protected from prolonged sun exposure. To avoid the Sun's strongest rays, limit exposure around the mid-day period. For minimizing sun-related eye damage, always choose sunglasses with UVA and UVB coverage. Note this! The Sun's UV radiation can nearly be doubled by the reflection off snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How cold is December in Alton?
What is the average humidity in December in Alton?
How much does it rain in Alton in December?
How much does it snow in Alton in December?
What is the month with the shortest days in Alton?
How many hours of daylight does Alton have in December?
When is the sunrise / sunset in December in Alton?
How long on average sun shines in December in Alton?
What are the months with the lowest UV index in Alton?
What is the UV index intensity in December in Alton?
Average temperature in December
Alton, IL
- Average high temperature in December: 41.2°F
The warmest month (with the highest average high temperature) is July (85.3°F).
The month with the lowest average high temperature is January (36.1°F).
- Average low temperature in December: 29.5°F
The month with the highest average low temperature is July (67.6°F).
The coldest month (with the lowest average low temperature) is January (23.2°F).
Average pressure in December
Alton, IL
- Average pressure in December: 30.13"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in December
Alton, IL
- Average wind speed in December: 9mph
The windiest month (with the highest average wind speed) is January (9.6mph).
The calmest month (with the lowest average wind speed) is July (5.7mph).
Average humidity in December
Alton, IL
- Average humidity in December: 77%
The month with the highest relative humidity is July (80%).
The month with the lowest relative humidity is October (71%).
Average rainfall in December
Alton, IL
- Average rainfall in December: 0.94"
The wettest month (with the highest rainfall) is May (2.44").
The driest month (with the least rainfall) is February (0.83").
Average rainfall days in December
Alton, IL
- Average rainfall days in December: 6.3 days
The month with the highest number of rainy days is July (15.4 days).
The month with the least rainy days is January (5.7 days).
Average snowfall in December
Alton, IL
- Average snowfall in December: 0.55"
The month with the highest snowfall is February (1.14").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in December
Alton, IL
- Average snowfall days in December: 3.6 days
The month with the highest number of snowfall days is January (5.4 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
Alton, IL
- Average daylight in December: 9h and 3min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 30min).
- Average sunshine in December: 4h and 5min
The month with the most sunshine is June (Average sunshine: 10h and 24min).
The months with the least sunshine are January and February (Average sunshine: 4h and 30min).
Average sunshine days in December
Alton, IL
- Average sunshine days in December: 21 days
The month with the most sunshine days is December (21 days).
The month with the least sunshine days is June (12.6 days).
Average UV index in December
Alton, 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
Alton, IL
- Average cloud cover in December: 49
The month with the most cloud cover is January (Cloud cover 52).
The month with the least cloud cover is August (Cloud cover 28).
Average visibility in December
Alton, 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).
Alton, Illinois, USA
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