December weather forecast and climate
Boulder, MT

Weather in December

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

The average relative humidity in December is 84%.

Rainfall

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

Snowfall

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

Daylight

The month with the shortest days in Boulder is December, with an average of 8.7h of daylight.

Sunshine

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

UV index

In Boulder, Montana, the average daily maximum UV index is 2. A UV Index value of 2, and less, symbolizes a minimal health hazard from unprotected exposure to the Sun's UV rays for the ordinary person.
Note: The average daily UV index of 2 in December transform into the following instructions:
Extended sun exposure is not an issue for the majority. Children, infants, and fair-skinned individuals always need to be protected. 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. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.
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FAQ

What is the coldest month in Boulder?

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.

What is the average humidity in December in Boulder?

In December, the average relative humidity in Boulder, Montana, 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 much does it rain in Boulder in December?

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, during 16.8 snowfall days, 6.22" (158mm) of snow is typically accumulated.

What is the month with the shortest days in Boulder?

With an average of 8.7h of daylight, December has the shortest days of the year.

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

The average length of the day in December in Boulder, Montana, is 8.7h.

What is the month with the least sunshine in Boulder?

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

How long on average sun shines in December in Boulder?

In December, the average sunshine is 5.6h.

How high is the UV index in December in Boulder?

The average daily maximum UV index in December is 2. A UV Index estimate of 2, and below, represents a minimal hazard to health from unsafe exposure to the Sun's UV rays.

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"

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

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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").
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).
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: 8.7h

The month with the longest days is June (Average daylight: 15.7h).
The month with the shortest days is December (Average daylight: 8.7h).

  • Average sunshine in December: 5.6h

The month with the most sunshine is July (Average sunshine: 11.7h).
Months with the least sunshine are January and December (Average sunshine: 5.6).

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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

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

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