December weather forecast
Winnetka, IL

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Weather in December

The first month of the winter, December, is still a cold month in Winnetka, Illinois, with an average temperature fluctuating between 34.9°F (1.6°C) and 26.1°F (-3.3°C).

Temperature

Winnetka's December weather shows a moderate shift in high-temperatures, falling from November's chilly 45.5°F (7.5°C) to a cold 34.9°F (1.6°C). The temperature in Winnetka during December nights demonstrates a small drop from the daytime highs, settling to an average of 26.1°F (-3.3°C).

Humidity

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

Rainfall

The month with the least rainfall in Winnetka is December, when the rain falls for 9.1 days and typically collects 1.65" (42mm) of precipitation.

Snowfall

Months with snowfall are January through May, October through December. In Winnetka, during December, snow falls for 10 days and regularly aggregates up to 2.99" (76mm) of snow. Throughout the year, there are 47.6 snowfall days, and 17.8" (452mm) of snow is accumulated.

Daylight

December has the shortest days of the year, with an average of 9h and 12min of daylight.
On the first day of December, sunrise is at 7:00 am and sunset at 4:20 pm. On the last day of the month, sunrise is at 7:19 am and sunset at 4:29 pm CST.

Sunshine

The average sunshine in December is 4h.

UV index

The month with the lowest UV index is December, with an average maximum UV index of 1. A UV Index of 2, and less, symbolizes a low health risk from unsafe exposure to UV radiation for average individuals.
Note: The maximum daily UV index of 1 in December interprets into the following recommendations:
Extended sun exposure is not an issue for the majority. Children, infants, and fair-skinned individuals always need to be protected. To guard against the harmful effects of the Sun, minimize exposure during midday. A wide-brimmed hat is a staple for defending the face, eyes, ears, and neck from the Sun. Consider carefully! The reflective quality of snow can almost double the intensity of the Sun's UV radiation.
Updated: Jul 14, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

How cold is it in December?

Winnetka in December has an average high-temperature of 34.9°F (1.6°C) and an average low-temperature of 26.1°F (-3.3°C).

What is the average humidity in December?

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

What is the driest month?

December is the month with the least rainfall. Rain falls for 9.1 days and accumulates 1.65" (42mm) of precipitation.

How many days does it rain in December?

In Winnetka, in December, it is raining for 9.1 days, with typically 1.65" (42mm) of accumulated precipitation.

How much does it snow in December?

In Winnetka, in December, during 10 snowfall days, 2.99" (76mm) of snow is typically accumulated.

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 Winnetka, the average day length in December is 9h and 10min.

When are sunrise and sunset in December?

In December, on the first day of the month, sunrise is at 7:00 am and sunset at 4:20 pm. On the last day of the month, sunrise is at 7:19 am and sunset at 4:29 pm CST.

How many hours of sunshine does Winnetka have in December?

In December, the average sunshine duration is 4h.

When is the lowest UV index?

The month with the lowest UV index is December, with an average maximum UV index of 1.

How high is the UV index in December?

The average daily maximum UV index in December is 1. A UV Index estimate of 2, and below, represents a low health risk from unprotected exposure to 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
Winnetka, IL

Average temperature in December - Winnetka, IL
  • Average high temperature in December: 34.9°F

The warmest month (with the highest average high temperature) is July (79.2°F).
The month with the lowest average high temperature is January (28.8°F).

  • Average low temperature in December: 26.1°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 (18.9°F).

Average pressure in December
Winnetka, IL

Average pressure in December - Winnetka, 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
Winnetka, IL

Average wind speed in December - Winnetka, IL
  • Average wind speed in December: 10.7mph

The windiest month (with the highest average wind speed) is January (11.5mph).
The calmest month (with the lowest average wind speed) is August (7.1mph).

Average humidity in December
Winnetka, IL

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

The month with the highest relative humidity is January (82%).
The month with the lowest relative humidity is October (73%).

Average rainfall in December
Winnetka, IL

Average rainfall in December - Winnetka, IL
  • Average rainfall in December: 1.65"

The wettest months (with the highest rainfall) are May and June (4.57").
The driest month (with the least rainfall) is December (1.65").

Average rainfall days in December
Winnetka, IL

Average rainfall days in December - Winnetka, IL
  • Average rainfall days in December: 9.1 days

The month with the highest number of rainy days is May (19.1 days).
The month with the least rainy days is February (6.1 days).

Average snowfall in December
Winnetka, IL

Average snowfall in December - Winnetka, IL
  • Average snowfall in December: 2.99"

The month with the highest snowfall is January (4.84").
The months with the least snowfall are June, July, August and September (0").

Average snowfall days in December
Winnetka, IL

Average snowfall days in December - Winnetka, IL
  • Average snowfall days in December: 10 days

The month with the highest number of snowfall days is January (13.1 days).
The months with the least snowfall days are June, July, August and September (0 days).

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

Average daylight in December / Average sunshine in December - Winnetka, 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 months with the most sunshine are July and August (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 3h and 42min).

Average sunshine days in December
Winnetka, IL

Average sunshine days in December - Winnetka, IL
  • Average sunshine days in December: 14.3 days

The month with the most sunshine days is November (15.5 days).
The month with the least sunshine days is June (9.2 days).

Average UV index in December
Winnetka, IL

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

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

Average cloud cover in December
Winnetka, IL

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

The month with the most cloud cover is January (Cloud cover 61).
The months with the least cloud cover are July and August (Cloud cover 28).

Average visibility in December
Winnetka, IL

Average visibility in December - Winnetka, 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).

Winnetka, Illinois, USA

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