December weather forecast
Joliet, IL

Share
A unique shot of cars, trees, and buildings along a street in the town of Joliet, Illinois
A unique shot of cars, trees, and buildings along a street in the town of Joliet, Illinois

Weather in December

December witnesses the advent of winter once more, closing the year with the second-highest snowfall estimated at 2.4" (61mm). The month’s average high caps at 35.1°F (1.7°C), reinforcing the frosty atmosphere of Joliet winters. Its freezing temperatures are accompanied by limited sunlight and extended nights. The wind retains its chilly sting and humidity remains high, ensuring a substantial likelihood of foggy mornings and evenings.

Temperature

The commencement of December in Joliet indicates a shift in the average high-temperature, receding from November's frosty 47.1°F (8.4°C) to an icy 35.1°F (1.7°C). Joliet's average low-temperature in the month of December is recorded at a freezing cold 25°F (-3.9°C).

Humidity

In December, the average relative humidity is 82%.

Rainfall

In December, the rain falls for 8.1 days. Throughout December, 1.69" (43mm) of precipitation is accumulated. In Joliet, during the entire year, the rain falls for 153.6 days and collects up to 32.72" (831mm) of precipitation.

Snowfall

January through April, November and December are months with snowfall in Joliet, Illinois. In December, it is snowing for 8 days. Throughout December, 2.4" (61mm) of snow is accumulated. In Joliet, during the entire year, snow falls for 38.2 days and aggregates up to 14.61" (371mm) of snow.

Daylight

With an average of 9h and 12min of daylight, December has the shortest days of the year in Joliet.
On the first day of December, sunrise is at 7:00 am and sunset at 4:23 pm. On the last day of the month, sunrise is at 7:18 am and sunset at 4:32 pm CST.

Sunshine

The average sunshine in December is 4.1h.

UV index

January and December, with an average maximum UV index of 1, are months with the lowest UV index in Joliet. A UV Index reading of 2, and below, represents a low threat to health from unsafe exposure to UV radiation for ordinary individuals.
Note: A maximum UV index of 1 in December translates into the following recommendations:
While sun exposure does not greatly affect most, individuals with fair skin, babies, and children always need vigilant safeguarding. Sun's radiation is most powerful around mid-day, so it's best to limit outdoor activities during this time. Opt for tightly woven and loose clothing to enhance protection from the Sun. Be informed! The Sun's UV radiation can be nearly doubled due to the reflection from snow.
[Resources]

Frequently asked questions

How cold is December in Joliet?

During December, Joliet experiences an average high-temperature of 35.1°F (1.7°C) and a low-temperature of 25°F (-3.9°C). In July, the average heat index (a.k.a. 'apparent temperature', 'felt air temperature'), which factors the actual air temperature with the relative humidity, is calculated to be 87.8°F (31°C).

What is the average humidity in December in Joliet?

The average relative humidity in December in Joliet, Illinois, is 82%.

How many days does it rain in December in Joliet?

In Joliet, Illinois, in December, it is raining for 8.1 days, with typically 1.69" (43mm) of accumulated precipitation.

How much does it snow in Joliet in December?

In Joliet, in December, snow falls for 8 days, with typically accumulated 2.4" (61mm) of snow.

What is the month with the shortest days in Joliet?

With an average of 9h and 12min of daylight, December has the shortest days of the year in Joliet.

What is the average length of the day in December in Joliet?

The average day length in December in Joliet is 9h and 14min.

When are sunrise and sunset in December in Joliet?

On the first day of December, sunrise is at 7:00 am and sunset at 4:23 pm. On the last day of the month, sunrise is at 7:18 am and sunset at 4:32 pm CST.

How long on average sun shines in December in Joliet?

In Joliet, Illinois, the average sunshine duration in December is 4.1h.

What are the months with the lowest UV index in Joliet?

January and December, with an average maximum UV index of 1, are months with the lowest UV index in Joliet.

How high is the UV index in December in Joliet?

In December, the average daily maximum UV index in Joliet, Illinois, is 1. A UV Index of 2, and less, symbolizes a low health risk 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
Joliet, IL

Average temperature in December - Joliet, IL
  • Average high temperature in December: 35.1°F

The warmest month (with the highest average high temperature) is July (81.3°F).
The month with the lowest average high temperature is January (29.3°F).

  • Average low temperature in December: 25°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 (17.4°F).

[Resources]

Average pressure in December
Joliet, IL

Average pressure in December - Joliet, IL
  • Average pressure in December: 30.1"Hg

The month with the highest atmospheric pressure is January (30.12"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).

[Resources]

Average wind speed in December
Joliet, IL

Average wind speed in December - Joliet, IL
  • Average wind speed in December: 8.9mph

The windiest month (with the highest average wind speed) is April (9.7mph).
The calmest month (with the lowest average wind speed) is August (5.9mph).

[Resources]

Average humidity in December
Joliet, IL

Average humidity in December - Joliet, IL
  • Average humidity in December: 82%

The month with the highest relative humidity is February (83%).
The month with the lowest relative humidity is October (73%).

[Resources]

Average rainfall in December
Joliet, IL

Average rainfall in December - Joliet, IL
  • Average rainfall in December: 1.69"

The wettest month (with the highest rainfall) is May (4.41").
The driest month (with the least rainfall) is February (1.61").

[Resources]

Average rainfall days in December
Joliet, IL

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

The month with the highest number of rainy days is July (17.9 days).
The month with the least rainy days is February (5.7 days).

[Resources]

Average snowfall in December
Joliet, IL

Average snowfall in December - Joliet, IL
  • Average snowfall in December: 2.4"

The month with the highest snowfall is January (4.33").
The months with the least snowfall are May, June, July, August, September and October (0").

[Resources]

Average snowfall days in December
Joliet, IL

Average snowfall days in December - Joliet, IL
  • Average snowfall days in December: 8 days

The month with the highest number of snowfall days is January (11.9 days).
The months with the least snowfall days are May, June, July, August and September (0 days).

[Resources]

Average daylight in December /
Average sunshine in December
Joliet, IL

Average daylight in December / Average sunshine in December - Joliet, 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 August (Average sunshine: 9h and 42min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).

[Resources]

Average sunshine days in December
Joliet, IL

Average sunshine days in December - Joliet, IL
  • Average sunshine days in December: 15.9 days

The month with the most sunshine days is November (18.1 days).
The month with the least sunshine days is June (10.4 days).

[Resources]

Average UV index in December
Joliet, IL

Average UV index in December - Joliet, IL
  • Average UV index in December: 1

The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January and December (UV index 1).

[Resources]

Average cloud cover in December
Joliet, IL

Average cloud cover in December - Joliet, IL
  • Average cloud cover in December: 58

The month with the most cloud cover is January (Cloud cover 60).
The months with the least cloud cover are August and September (Cloud cover 34).

[Resources]

Average visibility in December
Joliet, IL

Average visibility in December - Joliet, IL
  • Average visibility in December: 6mi

The months with the highest visibility are March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are January, February, July and August (5mi).

[Resources]

Joliet, Illinois, USA

Weather forecast for your location

1. Click Locate me button
2. Allow the app to use your location