December weather forecast
Piasa, IL

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Weather in December

The first month of the winter, December, is also an icy month in Piasa, Illinois, with temperature in the range of an average low of 29.3°F (-1.5°C) and an average high of 40.6°F (4.8°C).

Temperature

The beginning of December involves a decrease in the average high-temperature, transitioning from a fresh 51.6°F (10.9°C) in November to an icy 40.6°F (4.8°C). In Piasa, an average low-temperature of 29.3°F (-1.5°C) is recorded during December nights.

Humidity

In Piasa, the average relative humidity in December is 77%.

Rainfall

In Piasa, during December, the rain falls for 8.1 days and regularly aggregates up to 1.61" (41mm) of precipitation. Throughout the year, there are 141.9 rainfall days, and 27.36" (695mm) of precipitation is accumulated.

Snowfall

Months with snowfall are January through March, November and December. In Piasa, during December, snow falls for 3.9 days and regularly aggregates up to 1.73" (44mm) of snow. In Piasa, during the entire year, snow falls for 19.8 days and aggregates up to 7.91" (201mm) of snow.

Daylight

The month with the shortest days is December, with an average of 9h and 30min of daylight.
On the first day of the month, sunrise is at 7:01 am and sunset at 4:38 pm. On the last day of December, sunrise is at 7:19 am and sunset at 4:48 pm CST.

Sunshine

In Piasa, the average sunshine in December 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 rays for the average person.
Note: In December, a daily UV index of 2 turns into the following recommendations:
Prolonged sun exposure should always be prevented in babies, children, and those with sensitive skin. Direct Sun exposure should be minimized especially during midday when radiation is most intense. Experience reduced UV exposure by about half when donning a wide-brim hat. Be aware! The reflective nature of snow can magnify the Sun's UV radiation almost twofold.
Updated: Jun 24, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

How cold is it in December?

The average high-temperature, in December, in Piasa, is 40.6°F (4.8°C), while the average low-temperature is 29.3°F (-1.5°C). The average heat index (a.k.a. 'feels like', 'real feel'), which combines air temperature and relative humidity, in August is calculated to be 91.4°F (33°C).

What is the average humidity in December?

In Piasa, the average relative humidity in December is 77%.

How many days does it rain in December?

In Piasa, in December, during 8.1 rainfall days, 1.61" (41mm) of precipitation is typically accumulated.

How many days does it snow in December?

In December, it is snowing for 3.9 days. Throughout December, 1.73" (44mm) of snow is accumulated.

What is the month with the shortest days?

The month with the shortest days is December, with an average of 9h and 30min of daylight.

What is the average length of the day in December?

In December, the average day length is 9h and 28min.

When are sunrise and sunset in December?

In December, on the first day of the month, sunrise is at 7:01 am and sunset at 4:38 pm. On the last day of the month, in Piasa, sunrise is at 7:19 am and sunset at 4:48 pm CST.

How many hours of sunshine does Piasa have in December?

In December, the average sunshine duration is 4.9h.

What is the month with the lowest UV index?

The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 2.

What is the UV index intensity in December?

In Piasa, Illinois, the average daily maximum UV index in December is 2. A UV Index reading of 2, and below, represents a minimal health vulnerability from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
Piasa, IL

Average temperature in December - Piasa, IL
  • Average high temperature in December: 40.6°F

The warmest month (with the highest average high temperature) is July (84.6°F).
The month with the lowest average high temperature is January (35.8°F).

  • Average low temperature in December: 29.3°F

The month with the highest average low temperature is July (67.5°F).
The coldest month (with the lowest average low temperature) is January (22.6°F).

Average pressure in December
Piasa, IL

Average pressure in December - Piasa, IL
  • Average pressure in December: 30.13"Hg

The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

Average wind speed in December
Piasa, IL

Average wind speed in December - Piasa, IL
  • Average wind speed in December: 9.1mph

The windiest month (with the highest average wind speed) is January (9.8mph).
The calmest months (with the lowest average wind speed) are July and August (5.8mph).

Average humidity in December
Piasa, IL

Average humidity in December - Piasa, IL
  • Average humidity in December: 77%

The month with the highest relative humidity is July (81%).
The month with the lowest relative humidity is October (71%).

Average rainfall in December
Piasa, IL

Average rainfall in December - Piasa, IL
  • Average rainfall in December: 1.61"

The wettest month (with the highest rainfall) is June (3.35").
The driest month (with the least rainfall) is January (1.46").

Average rainfall days in December
Piasa, IL

Average rainfall days in December - Piasa, IL
  • Average rainfall days in December: 8.1 days

The month with the highest number of rainy days is May (16.7 days).
The month with the least rainy days is January (6.5 days).

Average snowfall in December
Piasa, IL

Average snowfall in December - Piasa, IL
  • Average snowfall in December: 1.73"

The month with the highest snowfall is February (2.48").
The months with the least snowfall are April, May, June, July, August, September and October (0").

Average snowfall days in December
Piasa, IL

Average snowfall days in December - Piasa, IL
  • Average snowfall days in December: 3.9 days

The month with the highest number of snowfall days is January (6.2 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
Piasa, IL

Average daylight in December / Average sunshine in December - Piasa, 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 18min).
The month with the least sunshine is January (Average sunshine: 4h and 24min).

Average sunshine days in December
Piasa, IL

Average sunshine days in December - Piasa, IL
  • Average sunshine days in December: 19.3 days

The month with the most sunshine days is January (19.5 days).
The month with the least sunshine days is July (12.1 days).

Average UV index in December
Piasa, IL

Average UV index in December - Piasa, IL
  • Average UV index in December: 2

The months with the highest UV index are May, 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
Piasa, IL

Average cloud cover in December - Piasa, IL
  • Average cloud cover in December: 49

The month with the most cloud cover is January (Cloud cover 52).
The months with the least cloud cover are August and September (Cloud cover 29).

Average visibility in December
Piasa, IL

Average visibility in December - Piasa, 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).

Piasa, Illinois, USA

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