December weather forecast
Lanark, IL

Share

Weather in December

December in Illinois marks the full onset of the winter season in Lanark. The month features the return of biting cold temperatures, takings the city back to a chilling atmosphere. During this period, snowfall peaks to 1.42" (36mm), painting the city white. The daylight hours withdraw to the year's lowest at 9.2 hours, making the days short and nights long. Depending on the incessant winds, the sharp winter chill deepens, setting the tone for the following year.

Temperature

The onset of December in Lanark is marked by a decrease in temperature, transitioning from a chilly 44.8°F (7.1°C) in November to an icy 32.5°F (0.3°C). An average low-temperature of 22.3°F (-5.4°C) is common during the nights of December.

Humidity

In December, the average relative humidity in Lanark, Illinois, is 83%.

Rainfall

In Lanark, in December, it is raining for 5.9 days, with typically 0.87" (22mm) of accumulated precipitation. Throughout the year, in Lanark, there are 130.8 rainfall days, and 17.95" (456mm) of precipitation is accumulated.

Snowfall

Months with snowfall in Lanark, Illinois, are January through April, October through December. In December, in Lanark, it is snowing for 8.6 days. Throughout December, 1.42" (36mm) of snow is accumulated. In Lanark, Illinois, during the entire year, snow falls for 39.2 days and aggregates up to 8.62" (219mm) of snow.

Daylight

With an average of 9h and 12min of daylight, December has the shortest days of the year in Lanark.
On the first day of December, sunrise is at 7:08 am and sunset at 4:28 pm. On the last day of the month, sunrise is at 7:27 am and sunset at 4:37 pm CST.

Sunshine

In December, the average sunshine in Lanark is 4h.

UV index

The months with the lowest UV index are January and December, with an average maximum UV index of 1. A UV Index reading of 2, and below, represents a low health risk from unprotected exposure to Sun's UV rays for the average person.
Note: An average UV index of 1 in December transforms into this advice:
Though the majority can handle prolonged sun exposure, it is crucial to always shield babies, children, and those with fair skin. Limiting exposure to the direct Sun during midday hours can help prevent harmful UV radiation effects. On sunny days, it's ideal to wear sunglasses that filter out UVA and UVB rays. Beware! Reflection from snow can magnify the Sun's UV radiation nearly twofold.
[Resources]

Frequently asked questions

How cold is December in Lanark?

An average high-temperature, in December, in Lanark, is 32.5°F (0.3°C) and the average low-temperature is 22.3°F (-5.4°C).

What is the average humidity in December in Lanark?

In December, the average relative humidity is 83%.

How many days does it rain in December in Lanark?

In Lanark, in December, it is raining for 5.9 days, with typically 0.87" (22mm) of accumulated precipitation.

How much does it snow in Lanark in December?

In December, it is snowing for 8.6 days. Throughout December, 1.42" (36mm) of snow is accumulated.

What is the month with the shortest days in Lanark?

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

How many hours of daylight does Lanark have in December?

The average day length in December in Lanark, Illinois, is 9h and 10min.

When are sunrise and sunset in December in Lanark?

In December, on the first day of the month, sunrise is at 7:08 am and sunset at 4:28 pm. On the last day of the month, sunrise is at 7:27 am and sunset at 4:37 pm CST.

How long on average sun shines in December in Lanark?

The average sunshine duration in December in Lanark is 4h.

What is the month with the lowest UV index in Lanark?

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

What is the UV index reading in December in Lanark?

The average daily maximum UV index in December in Lanark, Illinois, is 1. A UV Index reading of 2, and below, represents a minimal hazard to health from exposure to the Sun's UV radiation.
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
Lanark, IL

Average temperature in December - Lanark, IL
  • Average high temperature in December: 32.5°F

The warmest month (with the highest average high temperature) is July (79.9°F).
The month with the lowest average high temperature is January (25.9°F).

  • Average low temperature in December: 22.3°F

The month with the highest average low temperature is July (63.3°F).
The coldest month (with the lowest average low temperature) is January (13.5°F).

[Resources]

Average pressure in December
Lanark, IL

Average pressure in December - Lanark, 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 (29.91"Hg).

[Resources]

Average wind speed in December
Lanark, IL

Average wind speed in December - Lanark, IL
  • Average wind speed in December: 9.4mph

The windiest month (with the highest average wind speed) is April (10.4mph).
The calmest month (with the lowest average wind speed) is August (6.5mph).

[Resources]

Average humidity in December
Lanark, IL

Average humidity in December - Lanark, IL
  • Average humidity in December: 83%

The month with the highest relative humidity is January (87%).
The month with the lowest relative humidity is October (75%).

[Resources]

Average rainfall in December
Lanark, IL

Average rainfall in December - Lanark, IL
  • Average rainfall in December: 0.87"

The wettest month (with the highest rainfall) is May (2.76").
The driest months (with the least rainfall) are January and February (0.71").

[Resources]

Average rainfall days in December
Lanark, IL

Average rainfall days in December - Lanark, IL
  • Average rainfall days in December: 5.9 days

The month with the highest number of rainy days is May (17.9 days).
The month with the least rainy days is February (4.4 days).

[Resources]

Average snowfall in December
Lanark, IL

Average snowfall in December - Lanark, IL
  • Average snowfall in December: 1.42"

The month with the highest snowfall is January (2.64").
The months with the least snowfall are May, June, July, August and September (0").

[Resources]

Average snowfall days in December
Lanark, IL

Average snowfall days in December - Lanark, IL
  • Average snowfall days in December: 8.6 days

The month with the highest number of snowfall days is January (11.2 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
Lanark, IL

Average daylight in December / Average sunshine in December - Lanark, 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: 4h and 0min

The month with the most sunshine is July (Average sunshine: 9h and 48min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).

[Resources]

Average sunshine days in December
Lanark, IL

Average sunshine days in December - Lanark, IL
  • Average sunshine days in December: 18.4 days

The month with the most sunshine days is November (19.7 days).
The month with the least sunshine days is June (10 days).

[Resources]

Average UV index in December
Lanark, IL

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

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

[Resources]

Average cloud cover in December
Lanark, IL

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

The month with the most cloud cover is January (Cloud cover 61).
The month with the least cloud cover is September (Cloud cover 32).

[Resources]

Average visibility in December
Lanark, IL

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

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

[Resources]

Lanark, Illinois, USA

Weather forecast for your location

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