December weather forecast
Boulder, MT

Weather in December

December, the first month of the winter in Boulder, is still a freezing cold month, with temperature in the range of an average low of 12.6°F (-10.8°C) and an average high of 27°F (-2.8°C).

Temperature

With an average high-temperature of 27°F (-2.8°C) and an average low-temperature of 12.6°F (-10.8°C), December is the coldest month.

Humidity

In Boulder, Montana, the average relative humidity in December is 84%.

Rainfall

The month with the least rainfall in Boulder is December, when the rain falls for 8.2 days and typically collects 0.79" (20mm) of precipitation.

Snowfall

January through June, September through December are months with snowfall in Boulder. In Boulder, during December, snow falls for 16.8 days and regularly aggregates up to 6.22" (158mm) of snow. In Boulder, Montana, during the entire year, snow falls for 105.8 days and aggregates up to 55.12" (1400mm) of snow.

Daylight

December has the shortest days of the year, with an average of 8h and 41min of daylight.
On the first day of the month, sunrise is at 7:50 am and sunset at 4:44 pm. On the last day of December, in Boulder, sunrise is at 8:11 am and sunset at 4:51 pm MST.

Sunshine

The months with the least sunshine in Boulder are January and December, with an average of 5.6h of sunshine.

UV index

In December, the average daily maximum UV index is 2. A UV Index estimate of 2, and below, represents a low health risk from exposure to the Sun's UV radiation for the average person.
Note: The daily maximum UV index of 2 in December interpret into the following advice:
People with sensitive skin, children, and babies should always be protected from prolonged sun exposure. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. Caution! The reflection of snow can nearly double the intensity of the Sun's UV radiation.
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FAQ

What is the coldest month in Boulder?

December is the coldest month, with an average high-temperature of 27°F (-2.8°C) and an average low-temperature of 12.6°F (-10.8°C).

What is the temperature in December in Boulder?

In Boulder, in December, the average high-temperature is 27°F (-2.8°C), and the average low-temperature is 12.6°F (-10.8°C).

What is the average humidity in December in Boulder?

In Boulder, the average relative humidity in December is 84%.

What is the driest month in Boulder?

December is the month with the least rainfall in Boulder. Rain falls for 8.2 days and accumulates 0.79" (20mm) of precipitation.

How many days does it rain in December in Boulder?

In Boulder, in December, during 8.2 rainfall days, 0.79" (20mm) of precipitation is typically accumulated.

How many days does it snow in December in Boulder?

In Boulder, in December, snow falls for 16.8 days, with typically accumulated 6.22" (158mm) of snow.

What is the month with the shortest days in Boulder?

December has the shortest days of the year, with an average of 8h and 41min of daylight.

How many hours of daylight does Boulder have in December?

The average day length in December in Boulder is 8h and 41min.

When are sunrise and sunset in December in Boulder?

In December, on the first day of the month, sunrise is at 7:50 am and sunset at 4:44 pm. On the last day of the month, in Boulder, Montana, sunrise is at 8:11 am and sunset at 4:51 pm MST.

What is the month with the least sunshine in Boulder?

January and December, with an average of 5.6h of sunshine, are months with the least sunshine in Boulder.

How many hours of sunshine does Boulder have in December?

In December, the average sunshine duration in Boulder is 5.6h.

What is the UV index intensity in December in Boulder?

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

Average temperature in December - Boulder, MT
  • Average high temperature in December: 27°F

The warmest month (with the highest average high temperature) is July (79.7°F).
The month with the lowest average high temperature is December (27°F).

  • Average low temperature in December: 12.6°F

The month with the highest average low temperature is August (48.6°F).
The coldest month (with the lowest average low temperature) is December (12.6°F).

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Average pressure in December
Boulder, MT

Average pressure in December - Boulder, MT
  • Average pressure in December: 30.18"Hg

The month with the highest atmospheric pressure is January (30.19"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).

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Average wind speed in December
Boulder, MT

Average wind speed in December - Boulder, MT
  • Average wind speed in December: 6.4mph

The windiest months (with the highest average wind speed) are January and November (6.5mph).
The calmest month (with the lowest average wind speed) is August (4.7mph).

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Average humidity in December
Boulder, MT

Average humidity in December - Boulder, MT
  • Average humidity in December: 84%

The month with the highest relative humidity is January (86%).
The month with the lowest relative humidity is August (46%).

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Average rainfall in December
Boulder, MT

Average rainfall in December - Boulder, MT
  • Average rainfall in December: 0.79"

The wettest month (with the highest rainfall) is June (2.68").
The driest month (with the least rainfall) is December (0.79").

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Average rainfall days in December
Boulder, MT

Average rainfall days in December - Boulder, MT
  • Average rainfall days in December: 8.2 days

The month with the highest number of rainy days is May (18.2 days).
The month with the least rainy days is November (7.5 days).

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Average snowfall in December
Boulder, MT

Average snowfall in December - Boulder, MT
  • Average snowfall in December: 6.22"

The month with the highest snowfall is February (9.72").
The months with the least snowfall are July and August (0").

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Average snowfall days in December
Boulder, MT

Average snowfall days in December - Boulder, MT
  • Average snowfall days in December: 16.8 days

The month with the highest number of snowfall days is February (18 days).
The months with the least snowfall days are July and August (0 days).

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Average daylight in December /
Average sunshine in December
Boulder, MT

Average daylight in December / Average sunshine in December - Boulder, MT
  • Average daylight in December: 8h and 4min

The month with the longest days is June (Average daylight: 15h and 42min).
The month with the shortest days is December (Average daylight: 8h and 42min).

  • Average sunshine in December: 5h and 4min

The month with the most sunshine is July (Average sunshine: 11h and 42min).
The months with the least sunshine are January and December (Average sunshine: 5h and 36min).

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Average sunshine days in December
Boulder, MT

Average sunshine days in December - Boulder, MT
  • Average sunshine days in December: 13.7 days

The month with the most sunshine days is September (17.9 days).
The month with the least sunshine days is February (8.5 days).

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Average UV index in December
Boulder, MT

Average UV index in December - Boulder, MT
  • Average UV index in December: 2

The month with the highest UV index is July (UV index 6).
The month with the lowest UV index is February (UV index 1).

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Average cloud cover in December
Boulder, MT

Average cloud cover in December - Boulder, MT
  • Average cloud cover in December: 44

The month with the most cloud cover is February (Cloud cover 48).
The month with the least cloud cover is August (Cloud cover 15).

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Average visibility in December
Boulder, MT

Average visibility in December - Boulder, MT
  • Average visibility in December: 5mi

The months with the highest visibility are April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January, February, March and December (5mi).

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