December weather forecast
Janesville, WI

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Weather in December

December in Janesville, Wisconsin signals the full arrival of winter, resplendent with cold temperatures, snowfall, and the joyous holiday season. Snowfall increases to 1.61" (41mm) over a significantly higher 9.1 days. Winter sports enthusiasts can enjoy the snow-covered landscape, and families can engage in delightful Christmas festivities. This month embraces the chill and the gloom, replacing it with flickering lights and warm togetherness. December in Janesville leaves the year on a high note, dressing the city in snowy splendor and brimming holiday cheer.

Temperature

Janesville's weather in December involves a decrease in the average high-temperature, moving down from November's frosty 43.9°F (6.6°C) to a subzero cold 31.6°F (-0.2°C). Janesville, during December, witnesses an average low-temperature of 21.7°F (-5.7°C).

Humidity

In December, the average relative humidity is 83%.

Rainfall

In Janesville, in December, during 6.5 rainfall days, 0.79" (20mm) of precipitation is typically accumulated. Throughout the year, in Janesville, there are 127.7 rainfall days, and 17.87" (454mm) of precipitation is accumulated.

Snowfall

January through April, October through December are months with snowfall. In Janesville, Wisconsin, in December, snow falls for 9.1 days, with typically accumulated 1.61" (41mm) of snow. Throughout the year, there are 44.5 snowfall days, and 11.34" (288mm) of snow is accumulated.

Daylight

December has the shortest days of the year in Janesville, with an average of 9h and 6min of daylight.
On the first day of the month, sunrise is at 7:07 am and sunset at 4:23 pm. On the last day of December, in Janesville, sunrise is at 7:26 am and sunset at 4:32 pm CST.

Sunshine

The average sunshine in December in Janesville, Wisconsin, is 3.9h.

UV index

The months with the lowest UV index in Janesville are January and December, with an average maximum UV index of 1. A UV Index value of 2, and less, symbolizes a minimal health hazard from unprotected exposure to Sun's UV rays for ordinary individuals.
Note: In December, the UV index of 1 transforms into the following advice:
For the majority, extended sun exposure is not of great concern. Infants and people with sensitive skin must always be protected. UV radiation is strongest from the Sun during midday; protect yourself by staying in shaded areas. Counter UV radiation's ill effects with clothing designed for sun safety and UV-resistant eyewear. Be on the lookout! Nearly twofold UV radiation from the Sun can be reflected by snow.
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Frequently asked questions

How cold is it in Janesville in December?

In Janesville, in December, the average high-temperature is 31.6°F (-0.2°C), and the average low-temperature is 21.7°F (-5.7°C).

What is the average humidity in December in Janesville?

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

How much does it rain in Janesville in December?

In December, in Janesville, Wisconsin, the rain falls for 6.5 days. Throughout December, 0.79" (20mm) of precipitation is accumulated.

How much does it snow in Janesville in December?

In Janesville, in December, during 9.1 snowfall days, 1.61" (41mm) of snow is typically accumulated.

What is the month with the shortest days in Janesville?

December has the shortest days of the year in Janesville, with an average of 9h and 6min of daylight.

How many hours of daylight does Janesville have in December?

In December, the average day length is 9h and 7min.

When are sunrise and sunset in December in Janesville?

On the first day of December, sunrise is at 7:07 am and sunset at 4:23 pm. On the last day of the month, sunrise is at 7:26 am and sunset at 4:32 pm CST.

How long on average sun shines in December in Janesville?

In December, the average sunshine duration in Janesville, Wisconsin, is 3.9h.

When is the lowest UV index in Janesville?

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

How high is the UV index in December in Janesville?

In December, the average daily maximum UV index in Janesville is 1. A UV Index reading of 2, and below, represents a low health threat 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
Janesville, WI

Average temperature in December - Janesville, WI
  • Average high temperature in December: 31.6°F

The warmest month (with the highest average high temperature) is July (79.7°F).
The month with the lowest average high temperature is January (25°F).

  • Average low temperature in December: 21.7°F

The month with the highest average low temperature is July (62.4°F).
The coldest month (with the lowest average low temperature) is January (12.9°F).

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Average pressure in December
Janesville, WI

Average pressure in December - Janesville, WI
  • Average pressure in December: 30.09"Hg

The month with the highest atmospheric pressure is January (30.11"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).

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Average wind speed in December
Janesville, WI

Average wind speed in December - Janesville, WI
  • Average wind speed in December: 9.2mph

The windiest month (with the highest average wind speed) is April (10.1mph).
The calmest month (with the lowest average wind speed) is August (6.4mph).

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Average humidity in December
Janesville, WI

Average humidity in December - Janesville, WI
  • Average humidity in December: 83%

The month with the highest relative humidity is January (87%).
The months with the lowest relative humidity are April and October (76%).

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Average rainfall in December
Janesville, WI

Average rainfall in December - Janesville, WI
  • Average rainfall in December: 0.79"

The wettest month (with the highest rainfall) is June (2.76").
The driest months (with the least rainfall) are January and February (0.75").

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Average rainfall days in December
Janesville, WI

Average rainfall days in December - Janesville, WI
  • Average rainfall days in December: 6.5 days

The month with the highest number of rainy days is June (16.3 days).
The month with the least rainy days is January (3.5 days).

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Average snowfall in December
Janesville, WI

Average snowfall in December - Janesville, WI
  • Average snowfall in December: 1.61"

The month with the highest snowfall is January (2.83").
The months with the least snowfall are May, June, July, August and September (0").

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Average snowfall days in December
Janesville, WI

Average snowfall days in December - Janesville, WI
  • Average snowfall days in December: 9.1 days

The month with the highest number of snowfall days is January (12.5 days).
The months with the least snowfall days are June, July, August and September (0 days).

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Average daylight in December /
Average sunshine in December
Janesville, WI

Average daylight in December / Average sunshine in December - Janesville, WI
  • Average daylight in December: 9h and 1min

The month with the longest days is June (Average daylight: 15h and 18min).
The month with the shortest days is December (Average daylight: 9h and 6min).

  • Average sunshine in December: 3h and 5min

The months with the most sunshine are July and August (Average sunshine: 9h and 42min).
The month with the least sunshine is January (Average sunshine: 3h and 30min).

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Average sunshine days in December
Janesville, WI

Average sunshine days in December - Janesville, WI
  • Average sunshine days in December: 17.4 days

The month with the most sunshine days is November (19.1 days).
The month with the least sunshine days is June (10.9 days).

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Average UV index in December
Janesville, WI

Average UV index in December - Janesville, WI
  • Average UV index in December: 1

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

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Average cloud cover in December
Janesville, WI

Average cloud cover in December - Janesville, WI
  • Average cloud cover in December: 60

The month with the most cloud cover is January (Cloud cover 64).
The month with the least cloud cover is September (Cloud cover 34).

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Average visibility in December
Janesville, WI

Average visibility in December - Janesville, WI
  • Average visibility in December: 6mi

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

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Janesville, Wisconsin, USA

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