December weather forecast
Big Sky, MT

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Vast fields and planted forests near the scenic mountainous region in Big Sky, Montana
Vast fields and planted forests near the scenic mountainous region in Big Sky, Montana

Weather in December

December brings Big Sky full circle as it plunges back into the height of winter. The thermometer continues to drop, averaging highs of only 22.5°F (-5.3°C). Thunderous snowfall covers the town, preparing for an array of winter activities once again. Despite being the darkest month of the year, it can very much be the brightest, with Christmas lights sporadically punctuating the winter nights. December's weather wraps up the year on a chilly note, promising the return of the Big Sky winter wonderland.

Temperature

In Big Sky, Montana, December is the month with the lowest recorded average temperatures, measuring a high of 22.5°F (-5.3°C) and a low of 7.9°F (-13.4°C).

Humidity

The average relative humidity in December is 89%.

Rainfall

In Big Sky, in December, it is raining for 6.3 days, with typically 1.34" (34mm) of accumulated precipitation. Throughout the year, in Big Sky, Montana, there are 116.1 rainfall days, and 23.5" (597mm) of precipitation is accumulated.

Snowfall

January through December are months with snowfall in Big Sky, Montana. In Big Sky, in December, during 19.1 snowfall days, 11.1" (282mm) of snow is typically accumulated. In Big Sky, during the entire year, snow falls for 151.6 days and aggregates up to 124.06" (3151mm) of snow.

Daylight

December has the shortest days of the year, with an average of 8h and 48min of daylight.
On the first day of the month, sunrise is at 7:44 am and sunset at 4:44 pm. On the last day of December, in Big Sky, sunrise is at 8:04 am and sunset at 4:52 pm MST.

Sunshine

The average sunshine in December is 4.8h.

UV index

The average daily maximum UV index in December is 2. A UV Index of 2, and less, symbolizes a minimal health vulnerability from unprotected exposure to Sun's UV rays for average individuals.
Note: A daily high UV index of 2 in December leads to these guidelines:
Those with sensitive skin, infants, and children require constant safeguarding from prolonged sun exposure. To protect against the Sun's most potent rays, avoid direct exposure around midday. A wide-brimmed hat is a shield, deflecting up to 50% of harmful UV radiation from eyes. Stay alert! Snow's reflective properties can almost double the UV radiation from the Sun.
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Frequently asked questions

What is the coldest time of year in Big Sky?

The lowest temperatures are recorded in December, with averages reaching a high of 22.5°F (-5.3°C) and a low of 7.9°F (-13.4°C).

How cold is December in Big Sky?

In Big Sky, in December, the average high-temperature is 22.5°F (-5.3°C), and the average low-temperature is 7.9°F (-13.4°C).

What is the average humidity in December in Big Sky?

In Big Sky, the average relative humidity in December is 89%.

How much does it rain in Big Sky in December?

In Big Sky, Montana, in December, during 6.3 rainfall days, 1.34" (34mm) of precipitation is typically accumulated.

How much does it snow in Big Sky in December?

In Big Sky, Montana, in December, during 19.1 snowfall days, 11.1" (282mm) of snow is typically accumulated.

What is the month with the shortest days in Big Sky?

December has the shortest days of the year in Big Sky, Montana, with an average of 8h and 48min of daylight.

How many hours of daylight does Big Sky have in December?

In Big Sky, the average day length in December is 8h and 49min.

When is the sunrise / sunset in December in Big Sky?

On the first day of December in Big Sky, sunrise is at 7:44 am and sunset at 4:44 pm. On the last day of the month, sunrise is at 8:04 am and sunset at 4:52 pm MST.

How long on average sun shines in December in Big Sky?

In Big Sky, Montana, the average sunshine duration in December is 4.8h.

What is the UV index reading in December in Big Sky?

In Big Sky, Montana, the average daily maximum UV index in December is 2. A UV Index estimate 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
Big Sky, MT

Average temperature in December - Big Sky, MT
  • Average high temperature in December: 22.5°F

The warmest month (with the highest average high temperature) is July (74.8°F).
The month with the lowest average high temperature is December (22.5°F).

  • Average low temperature in December: 7.9°F

The month with the highest average low temperature is August (45.1°F).
The coldest month (with the lowest average low temperature) is December (7.9°F).

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Average pressure in December
Big Sky, MT

Average pressure in December - Big Sky, MT
  • Average pressure in December: 30.21"Hg

The month with the highest atmospheric pressure is January (30.22"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).

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Average wind speed in December
Big Sky, MT

Average wind speed in December - Big Sky, MT
  • Average wind speed in December: 6.8mph

The windiest month (with the highest average wind speed) is January (7.1mph).
The calmest month (with the lowest average wind speed) is August (4.8mph).

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Average humidity in December
Big Sky, MT

Average humidity in December - Big Sky, MT
  • Average humidity in December: 89%

The months with the highest relative humidity are January and February (90%).
The month with the lowest relative humidity is August (51%).

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Average rainfall in December
Big Sky, MT

Average rainfall in December - Big Sky, MT
  • Average rainfall in December: 1.34"

The wettest months (with the highest rainfall) are April and May (2.91").
The driest month (with the least rainfall) is July (1.18").

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Average rainfall days in December
Big Sky, MT

Average rainfall days in December - Big Sky, MT
  • Average rainfall days in December: 6.3 days

The month with the highest number of rainy days is June (16.6 days).
The month with the least rainy days is February (4.3 days).

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Average snowfall in December
Big Sky, MT

Average snowfall in December - Big Sky, MT
  • Average snowfall in December: 11.1"

The month with the highest snowfall is April (19.88").
The month with the least snowfall is August (0.08").

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Average snowfall days in December
Big Sky, MT

Average snowfall days in December - Big Sky, MT
  • Average snowfall days in December: 19.1 days

The month with the highest number of snowfall days is March (21 days).
The month with the least snowfall days is August (0.3 days).

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Average daylight in December /
Average sunshine in December
Big Sky, MT

Average daylight in December / Average sunshine in December - Big Sky, MT
  • Average daylight in December: 8h and 5min

The month with the longest days is June (Average daylight: 15h and 36min).
The month with the shortest days is December (Average daylight: 8h and 48min).

  • Average sunshine in December: 4h and 5min

The month with the most sunshine is July (Average sunshine: 11h and 42min).
The month with the least sunshine is January (Average sunshine: 4h and 42min).

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Average sunshine days in December
Big Sky, MT

Average sunshine days in December - Big Sky, MT
  • Average sunshine days in December: 12.2 days

The month with the most sunshine days is September (14.5 days).
The month with the least sunshine days is May (5.7 days).

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Average UV index in December
Big Sky, MT

Average UV index in December - Big Sky, MT
  • Average UV index in December: 2

The month with the highest UV index is July (UV index 5).
The months with the lowest UV index are January and February (UV index 1).

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Average cloud cover in December
Big Sky, MT

Average cloud cover in December - Big Sky, MT
  • Average cloud cover in December: 56

The month with the most cloud cover is February (Cloud cover 60).
The month with the least cloud cover is July (Cloud cover 17).

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Average visibility in December
Big Sky, MT

Average visibility in December - Big Sky, MT
  • Average visibility in December: 4mi

The months with the highest visibility are June, July, August, September and October (6mi).
The months with the lowest visibility are January, February, March, April and December (4mi).

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Big Sky, Montana, USA

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