Boulder
Montana, USA
Long-term weather forecast
Long-term weather forecast

December weather forecast and climate
Boulder, MT

December, the first month of the winter, in Boulder, is also a subzero cold month, with average temperature ranging between max 27°F (-2.8°C) and min 32°F (0°C).

Temperature

December is the coldest month, with an average high-temperature of 27°F (-2.8°C) and an average low-temperature of 32°F (0°C).

Humidity

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

Rainfall

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

Snowfall

Months with snowfall in Boulder are January through June, September through December. 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

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

Sunshine

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

UV index

In December, the average daily maximum UV index is 2. A UV Index of 2, and less, symbolizes a minimal health vulnerability from unprotected exposure to the Sun's UV rays for ordinary individuals.
Note: In December, the average maximum UV index of 2 translate into the following recommendations:
For the majority, extended sun exposure is not of great concern. Infants and people with sensitive skin must always be protected. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.

What is the coldest month in Boulder?

The coldest month is December, with an average high-temperature of 27°F (-2.8°C) and an average low-temperature of 32°F (0°C).

What is the temperature in December in Boulder?

In December, in Boulder, the average high-temperature is 27°F (-2.8°C), and the average low-temperature is 32°F (0°C).

What is the average humidity in December in Boulder?

The average relative humidity in December is 84%.

How many days does it rain in December in Boulder?

In December, the rain falls for 8.2 days. Throughout December, 0.79" (20mm) of precipitation is accumulated.

What is the driest month in Boulder?

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

How many days does it snow in December in Boulder?

In Boulder, Montana, 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?

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

How many hours of daylight does Boulder have in December?

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

What is the month with the least sunshine in Boulder?

Months with the least sunshine in Boulder, Montana, 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 in Boulder 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 reading of 2, and below, represents a low health threat from unprotected exposure to the UV radiation.
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: 0°F

Months with the highest average low temperature are January, February, March, April, May, June, July, August, September, October, November and December (0°F).
Coldest months (with the lowest average low temperature) are January, February, March, April, May, June, July, August, September, October, November and December (0°F).

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%).

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 lowest rainfall) is December (0.79").

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 lowest number of rainy days is November (7.5 days).

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 lowest snowfall are July and August (0").

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 lowest number of snowfall days are July and August (0 days).

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 shortest days is December (Average daylight: 8.7h).

  • Average sunshine in December: 5.6h

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

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).