December weather forecast
Winnetka, IL

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Weather in December

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

Temperature

With the onset of December, Winnetka experiences a modest temperature adjustment, with the average high-temperature receding from a chilly 45.5°F (7.5°C) in November to a cold 34.9°F (1.6°C). Winnetka's average temperature throughout the nights in December exhibits a minor decrease from daytime highs, stabilizing at a subzero cold 26.1°F (-3.3°C).

Humidity

The average relative humidity in December in Winnetka is 80%.

Rainfall

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

Snowfall

January through May, October through December are months with snowfall in Winnetka, Illinois. In December, in Winnetka, it is snowing for 10 days. Throughout December, 2.99" (76mm) of snow is accumulated. Throughout the year, there are 47.6 snowfall days, and 17.8" (452mm) of snow is accumulated.

Daylight

With an average of 9h and 12min of daylight, December has the shortest days of the year.
On the first day of the month, sunrise is at 7:00 am and sunset at 4:20 pm. On the last day of December, in Winnetka, 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 minimal health hazard from exposure to the Sun's UV radiation for the ordinary person.
Note: In December, the maximum UV index of 1 translates into these guidelines:
Most individuals face no major issues with lengthy exposure to the sun, but children, infants, and individuals with fair skin always require protection. When the Sun is at its strongest around midday, find shade and limit exposure. For excellent sun protection for the eyes, ears, face, and neck, consider a wide-brim hat. Take warning! The intensity of the Sun's UV radiation can be nearly amplified twice due to snow reflection.
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Frequently asked questions

How cold is December in Winnetka?

The average high-temperature, in December, in Winnetka, is 34.9°F (1.6°C), while the average low-temperature is 26.1°F (-3.3°C).

What is the average humidity in December in Winnetka?

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

What is the driest month in Winnetka?

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

How much does it rain in Winnetka in December?

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

How many days does it snow in December in Winnetka?

In Winnetka, in December, snow falls for 10 days, with typically accumulated 2.99" (76mm) of snow.

What is the month with the shortest days in Winnetka?

The month with the shortest days in Winnetka, Illinois, is December, with an average of 9h and 12min of daylight.

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

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

When is the sunrise / sunset in December in Winnetka?

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.

How many hours of sunshine does Winnetka have in December?

In December, the average sunshine duration is 4h.

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

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

What is the UV index reading in December in Winnetka?

The average daily maximum UV index in December in Winnetka, Illinois, is 1. A UV Index reading of 2, and below, represents a low health risk from unsafe 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
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).

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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).

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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).

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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%).

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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").

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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).

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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").

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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).

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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).

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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).

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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).

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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).

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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).

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Winnetka, Illinois, USA

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