December weather forecast
Swansea, IL

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Weather in December

The first month of the winter, December, is also an icy month in Swansea, Illinois, with temperature in the range of an average low of 30.6°F (-0.8°C) and an average high of 42.6°F (5.9°C).

Temperature

A shift in the average high-temperature occurs in December, reducing from a cool 53.4°F (11.9°C) in November to a wintry 42.6°F (5.9°C). Swansea cools down to an average low-temperature of 30.6°F (-0.8°C) throughout the month of December.

Humidity

The average relative humidity in December is 76%.

Rainfall

In December, the rain falls for 8.4 days. Throughout December, 2.28" (58mm) of precipitation is accumulated. Throughout the year, there are 147.1 rainfall days, and 35.43" (900mm) of precipitation is accumulated.

Snowfall

Months with snowfall are January through March, November and December. In Swansea, during December, snow falls for 4 days and regularly aggregates up to 2.01" (51mm) of snow. Throughout the year, there are 21.1 snowfall days, and 8.11" (206mm) of snow is accumulated.

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 6:59 am and sunset at 4:39 pm. On the last day of December, sunrise is at 7:17 am and sunset at 4:49 pm CST.

Sunshine

In December, the average sunshine is 4.7h.

UV index

January, February 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 minimal health hazard from exposure to the Sun's UV radiation for ordinary individuals.
Note: A daily high UV index of 2 in December leads to these guidelines:
Children, infants, and individuals with sensitive skin should be constantly protected from extended sun exposure. It's crucial to reduce time in the direct Sun around mid-day due to the intense solar radiation. For effective sun eye protection, rely on sunglasses certified for UVA and UVB resistance. Warning! The reflection from snow can nearly magnify the Sun's UV radiation twofold.
Updated: Aug 23, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

Is December cold?

The high-temperature, in December, in Swansea, records 42.6°F (5.9°C), while the low-temperature is 30.6°F (-0.8°C). The average heat index (a.k.a. 'felt air temperature', 'feels like'), which factors the actual air temperature with the relative humidity, in August is evaluated at 95°F (35°C).

What is the average humidity in December?

In December, the average relative humidity is 76%.

How many days does it rain in December?

In Swansea, during December, the rain falls for 8.4 days and regularly aggregates up to 2.28" (58mm) of precipitation.

How much does it snow in Swansea in December?

In Swansea, Illinois, in December, snow falls for 4 days, with typically accumulated 2.01" (51mm) of snow.

What is the month with the shortest days?

With an average of 9h and 30min of daylight, December has the shortest days of the year.

What is the average length of the day in December?

The average day length in December is 9h and 32min.

When are sunrise and sunset in December?

On the first day of December, sunrise is at 6:59 am and sunset at 4:39 pm. On the last day of the month, sunrise is at 7:17 am and sunset at 4:49 pm CST.

How many hours of sunshine does Swansea have in December?

In Swansea, Illinois, the average sunshine duration in December is 4.7h.

What are the months with the lowest UV index?

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

What is the UV index reading in December?

The average daily maximum UV index in December is 2. A UV Index estimate of 2, and below, represents a low health risk 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
Swansea, IL

Average temperature in December - Swansea, IL
  • Average high temperature in December: 42.6°F

The warmest month (with the highest average high temperature) is July (85.8°F).
The month with the lowest average high temperature is January (37.8°F).

  • Average low temperature in December: 30.6°F

The month with the highest average low temperature is July (68.4°F).
The coldest month (with the lowest average low temperature) is January (24.8°F).

Average pressure in December
Swansea, IL

Average pressure in December - Swansea, 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
Swansea, IL

Average wind speed in December - Swansea, IL
  • Average wind speed in December: 8.7mph

The windiest month (with the highest average wind speed) is January (9.4mph).
The calmest month (with the lowest average wind speed) is July (5.6mph).

Average humidity in December
Swansea, IL

Average humidity in December - Swansea, IL
  • Average humidity in December: 76%

The months with the highest relative humidity are May and July (79%).
The month with the lowest relative humidity is October (71%).

Average rainfall in December
Swansea, IL

Average rainfall in December - Swansea, IL
  • Average rainfall in December: 2.28"

The wettest month (with the highest rainfall) is May (4.37").
The driest month (with the least rainfall) is February (1.93").

Average rainfall days in December
Swansea, IL

Average rainfall days in December - Swansea, IL
  • Average rainfall days in December: 8.4 days

The month with the highest number of rainy days is May (16.4 days).
The month with the least rainy days is January (6.8 days).

Average snowfall in December
Swansea, IL

Average snowfall in December - Swansea, IL
  • Average snowfall in December: 2.01"

The month with the highest snowfall is January (2.4").
The months with the least snowfall are April, May, June, July, August, September and October (0").

Average snowfall days in December
Swansea, IL

Average snowfall days in December - Swansea, IL
  • Average snowfall days in December: 4 days

The month with the highest number of snowfall days is January (7.3 days).
The months with the least snowfall days are May, June, July and August (0 days).

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

Average daylight in December / Average sunshine in December - Swansea, IL
  • Average daylight in December: 9h and 3min

The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 30min).

  • Average sunshine in December: 4h and 4min

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 30min).

Average sunshine days in December
Swansea, IL

Average sunshine days in December - Swansea, IL
  • Average sunshine days in December: 18.2 days

The month with the most sunshine days is October (18.3 days).
The month with the least sunshine days is May (12.3 days).

Average UV index in December
Swansea, IL

Average UV index in December - Swansea, 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 and December (UV index 2).

Average cloud cover in December
Swansea, IL

Average cloud cover in December - Swansea, IL
  • Average cloud cover in December: 50

The month with the most cloud cover is January (Cloud cover 52).
The month with the least cloud cover is June (Cloud cover 29).

Average visibility in December
Swansea, IL

Average visibility in December - Swansea, 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).

Swansea, Illinois, USA

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