December weather forecast
Berwyn, IL

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Weather in December

December welcomes the peak winter season in Berwyn, characterized by the lowest temperatures of the year and frequent snowfall. The month is significantly colder compared to November, leading to much shorter days and longer nights. An important parameter of December’s weather lies in its lowest temperature extremes, which average around 26.4°F (-3.1°C). Limited sunshine hours and thick cloud cover contribute to December's colder climate, often leading to indoor-bound activities. Consequently, the town of Berwyn gets transformed into a winter wonderland in December, marking the end of the annual weather calendar.

Temperature

The start of December involves a temperature drop, moving from a frosty 46°F (7.8°C) in November to a wintry 35.1°F (1.7°C). Berwyn encounters a small divergence from daytime high temperatures, averaging a low-temperature of 26.4°F (-3.1°C) during December nights.

Humidity

In Berwyn, the average relative humidity in December is 80%.

Rainfall

February, March, November and December are months with the least rain when the rain falls for 4.3 days and typically aggregates up to 0.39" (10mm) of rain.

Snowfall

Months with snowfall are January through April, October through December. In Berwyn, during December, snow falls for 4.5 days and regularly aggregates up to 0.28" (7mm) of snow. In Berwyn, during the entire year, snow falls for 26.5 days and aggregates up to 4.06" (103mm) of snow.

Daylight

With an average of 9h and 12min of daylight, December has the shortest days of the year.
On the first day of December, sunrise is at 6:59 am and sunset at 4:21 pm. On the last day of the month, sunrise is at 7:18 am and sunset at 4:30 pm CST.

Sunshine

In December, the average sunshine is 4.1h.

UV index

The months with the lowest UV index are January and December, with an average maximum UV index of 1. A UV Index value of 2, and less, symbolizes a low threat to health from unprotected exposure to Sun's UV rays for ordinary individuals.
Note: An average UV index of 1 in December transforms into this advice:
Many can withstand an hour in the sun without burning, yet children must always have protection against sunlight. Direct Sun exposure should be minimized especially during midday when radiation is most intense. To mitigate harm from sun exposure, pick sunglasses offering UVA and UVB defense. Heads up! The UV radiation from the Sun can almost be doubled by snow reflection.
Updated: Aug 16, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

How cold is December?

In December, in Berwyn, the average high-temperature is 35.1°F (1.7°C), and the average low-temperature is 26.4°F (-3.1°C).

What is the average humidity in December?

In December, the average relative humidity in Berwyn is 80%.

What is the driest month?

February, March, November and December are months with the least rain when the rain falls for 4.3 days and typically aggregates up to 0.39" (10mm) of rain.

How many days does it rain in December?

In Berwyn, in December, during 4.3 rainfall days, 0.39" (10mm) of precipitation is typically accumulated.

How much does it snow in Berwyn in December?

In Berwyn, in December, snow falls for 4.5 days, with typically accumulated 0.28" (7mm) of snow.

What is the month with the shortest days?

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

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

The average day length in December is 9h and 12min.

When is the sunrise / sunset in December?

On the first day of December, sunrise is at 6:59 am and sunset at 4:21 pm. On the last day of the month, sunrise is at 7:18 am and sunset at 4:30 pm CST.

How many hours of sunshine does Berwyn have in December?

In December, the average sunshine duration is 4.1h.

When is the lowest UV index?

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

How high is the UV index in December?

In Berwyn, the average daily maximum UV index in December is 1. A UV Index estimate of 2, and below, represents a minimal hazard to health from 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
Berwyn, IL

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

The warmest month (with the highest average high temperature) is July (80.4°F).
The month with the lowest average high temperature is January (29.1°F).

  • Average low temperature in December: 26.4°F

The month with the highest average low temperature is July (67.1°F).
The coldest month (with the lowest average low temperature) is January (19.2°F).

Average pressure in December
Berwyn, IL

Average pressure in December - Berwyn, IL
  • 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 (29.92"Hg).

Average wind speed in December
Berwyn, IL

Average wind speed in December - Berwyn, IL
  • Average wind speed in December: 10.3mph

The windiest month (with the highest average wind speed) is January (10.9mph).
The calmest month (with the lowest average wind speed) is August (6.8mph).

Average humidity in December
Berwyn, IL

Average humidity in December - Berwyn, IL
  • Average humidity in December: 80%

The months with the highest relative humidity are January and February (82%).
The month with the lowest relative humidity is October (72%).

Average rainfall in December
Berwyn, IL

Average rainfall in December - Berwyn, IL
  • Average rainfall in December: 0.39"

The wettest month (with the highest rainfall) is May (1.1").
The driest months (with the least rainfall) are February, March, November and December (0.39").

Average rainfall days in December
Berwyn, IL

Average rainfall days in December - Berwyn, IL
  • Average rainfall days in December: 4.3 days

The month with the highest number of rainy days is June (11.7 days).
The month with the least rainy days is January (3.1 days).

Average snowfall in December
Berwyn, IL

Average snowfall in December - Berwyn, IL
  • Average snowfall in December: 0.28"

The month with the highest snowfall is February (1.38").
The months with the least snowfall are May, June, July, August and September (0").

Average snowfall days in December
Berwyn, IL

Average snowfall days in December - Berwyn, IL
  • Average snowfall days in December: 4.5 days

The month with the highest number of snowfall days is February (7.3 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
Berwyn, IL

Average daylight in December / Average sunshine in December - Berwyn, 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 1min

The month with the most sunshine is August (Average sunshine: 10h and 36min).
The month with the least sunshine is January (Average sunshine: 3h and 48min).

Average sunshine days in December
Berwyn, IL

Average sunshine days in December - Berwyn, IL
  • Average sunshine days in December: 23.7 days

The month with the most sunshine days is December (23.7 days).
The month with the least sunshine days is June (14.3 days).

Average UV index in December
Berwyn, IL

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

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

Average cloud cover in December
Berwyn, IL

Average cloud cover in December - Berwyn, 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 August (Cloud cover 27).

Average visibility in December
Berwyn, IL

Average visibility in December - Berwyn, 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).

Berwyn, Illinois, USA

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