December weather forecast
Troy, IL

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Weather in December

The first month of the winter, December, is still a cold month in Troy, Illinois, with an average temperature fluctuating between 30°F (-1.1°C) and 41.9°F (5.5°C).

Temperature

Troy, Illinois, in December undergoes a mild reduction in the average high-temperature, shifting from November's fresh 52.9°F (11.6°C) to a wintry 41.9°F (5.5°C). Troy reports an average nighttime low-temperature of 30°F (-1.1°C) in December.

Humidity

In Troy, the average relative humidity in December is 77%.

Rainfall

In Troy, during December, the rain falls for 8.4 days and regularly aggregates up to 2.2" (56mm) of precipitation. In Troy, during the entire year, the rain falls for 149.9 days and collects up to 33.94" (862mm) of precipitation.

Snowfall

January through March, September, November and December are months with snowfall. In Troy, in December, during 3.8 snowfall days, 1.73" (44mm) of snow is typically accumulated. Throughout the year, there are 20.7 snowfall days, and 7.13" (181mm) of snow is accumulated.

Daylight

With an average of 9h and 30min of daylight, December has the shortest days of the year.
On the first day of the month, sunrise is at 6:59 am and sunset at 4:38 pm. On the last day of December, sunrise is at 7:17 am and sunset at 4:48 pm CST.

Sunshine

The average sunshine in December is 4.8h.

UV index

January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index of 2, and less, symbolizes a low threat to health from exposure to the Sun's UV rays for the average person.
Note: In December, the UV index of 2 transforms into the following advice:
Prolonged sun exposure should always be prevented in babies, children, and those with sensitive skin. Being in direct Sun during midday can be harmful due to intense solar radiation; take precautions. A wide-brim hat offers excellent sun protection for the eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Observe! Snow reflection can nearly intensify the Sun's UV radiation twofold.
Updated: Aug 11, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

How cold is December?

An average high-temperature, in December, in Troy, is 41.9°F (5.5°C) and the average low-temperature is 30°F (-1.1°C). In August, the average heat index (a.k.a. 'real feel', 'felt air temperature'), which combines relative humidity and air temperature, is appraised at 93.2°F (34°C).

What is the average humidity in December?

In December, the average relative humidity is 77%.

How many days does it rain in December?

In Troy, during December, the rain falls for 8.4 days and regularly aggregates up to 2.2" (56mm) of precipitation.

How much does it snow in December?

In Troy, in December, during 3.8 snowfall days, 1.73" (44mm) of snow is typically accumulated.

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 in Troy.

How many hours of daylight does Troy have in December?

In December, the average day length is 9h and 31min.

When is the sunrise / sunset in December in Troy?

On the first day of December in Troy, sunrise is at 6:59 am and sunset at 4:38 pm. On the last day of the month, sunrise is at 7:17 am and sunset at 4:48 pm CST.

How many hours of sunshine does Troy have in December?

In Troy, the average sunshine duration in December is 4.8h.

What is the month with the lowest UV index?

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

How high is the UV index in December?

The average daily maximum UV index in December is 2. A UV Index reading of 2, and below, represents a minimal health vulnerability 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
Troy, IL

Average temperature in December - Troy, IL
  • Average high temperature in December: 41.9°F

The warmest month (with the highest average high temperature) is July (85.6°F).
The month with the lowest average high temperature is January (37.4°F).

  • Average low temperature in December: 30°F

The month with the highest average low temperature is July (68.2°F).
The coldest month (with the lowest average low temperature) is January (24.3°F).

Average pressure in December
Troy, IL

Average pressure in December - Troy, 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
Troy, IL

Average wind speed in December - Troy, IL
  • Average wind speed in December: 8.8mph

The windiest month (with the highest average wind speed) is January (9.5mph).
The calmest month (with the lowest average wind speed) is July (5.6mph).

Average humidity in December
Troy, IL

Average humidity in December - Troy, IL
  • Average humidity in December: 77%

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

Average rainfall in December
Troy, IL

Average rainfall in December - Troy, IL
  • Average rainfall in December: 2.2"

The wettest month (with the highest rainfall) is May (4.17").
The driest month (with the least rainfall) is February (1.77").

Average rainfall days in December
Troy, IL

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

The month with the highest number of rainy days is May (17.1 days).
The month with the least rainy days is January (7.8 days).

Average snowfall in December
Troy, IL

Average snowfall in December - Troy, IL
  • Average snowfall in December: 1.73"

The month with the highest snowfall is January (2.13").
The months with the least snowfall are April, May, June, July, August and October (0").

Average snowfall days in December
Troy, IL

Average snowfall days in December - Troy, IL
  • Average snowfall days in December: 3.8 days

The month with the highest number of snowfall days is January (7 days).
The months with the least snowfall days are May, June, July and August (0 days).

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

Average daylight in December / Average sunshine in December - Troy, 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 5min

The month with the most sunshine is June (Average sunshine: 10h and 30min).
The month with the least sunshine is January (Average sunshine: 4h and 30min).

Average sunshine days in December
Troy, IL

Average sunshine days in December - Troy, IL
  • Average sunshine days in December: 18.6 days

The month with the most sunshine days is December (18.6 days).
The month with the least sunshine days is May (11.6 days).

Average UV index in December
Troy, IL

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

Average cloud cover in December
Troy, IL

Average cloud cover in December - Troy, IL
  • Average cloud cover in December: 49

The month with the most cloud cover is January (Cloud cover 51).
The months with the least cloud cover are June and August (Cloud cover 28).

Average visibility in December
Troy, IL

Average visibility in December - Troy, 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).

Troy, Illinois, USA

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