December weather forecast
Boulder, WY

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Weather in December

Boulder bids the year farewell with a return to harsh winter conditions in December. The cold intensifies with temperatures dipping further to a monthly mean low of 5.9°F (-14.5°C), closing the year on a frosty note. Plus, a snowfall increment to 4.33" (110mm) accentuates the winter atmosphere. The onset of winter has its charming side as well, transforming the landscape into a snowy wonderland. As the year ends, residents hunker down for the holiday season in preparation for the new year ahead.

Temperature

December is the coldest month in Boulder, with an average high-temperature of 23.9°F (-4.5°C) and an average low-temperature of 5.9°F (-14.5°C).

Humidity

The average relative humidity in December in Boulder, Wyoming, is 83%.

Rainfall

In Boulder, Wyoming, in December, it is raining for 7.2 days, with typically 0.55" (14mm) of accumulated precipitation. In Boulder, Wyoming, during the entire year, the rain falls for 102.6 days and collects up to 10.75" (273mm) of precipitation.

Snowfall

Months with snowfall are January through June, September through December. In Boulder, during December, snow falls for 13.5 days and regularly aggregates up to 4.33" (110mm) of snow. Throughout the year, in Boulder, there are 86.8 snowfall days, and 41.77" (1061mm) of snow is accumulated.

Daylight

The month with the shortest days is December, with an average of 9h and 6min of daylight.
On the first day of the month, sunrise is at 7:30 am and sunset at 4:46 pm. On the last day of December, sunrise is at 7:49 am and sunset at 4:55 pm MST.

Sunshine

In Boulder, Wyoming, the average sunshine in December is 6.5h.

UV index

The months with the lowest UV index are January through April, October through December, with an average maximum UV index of 2. A UV Index reading of 2, and below, represents a low threat to health from unprotected exposure to Sun's UV rays for the ordinary person.
Note: The maximum daily UV index, 2 in December, converts into the following recommendations:
Children, babies, and those with sensitive skin should always be shielded from long periods of sun exposure. Considering the Sun's intensity during midday, it's wise to minimize direct exposure. For effective sun eye protection, rely on sunglasses certified for UVA and UVB resistance. Be careful! The Sun's UV radiation can nearly be doubled by the reflective quality of snow.
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Frequently asked questions

What is the coldest month in Boulder?

December proves to be the coldest month in Boulder, recording an average maximum temperature of 23.9°F (-4.5°C) and a minimum temperature of 5.9°F (-14.5°C).

How cold is December in Boulder?

During December, Boulder experiences an average high-temperature of 23.9°F (-4.5°C) and a low-temperature of 5.9°F (-14.5°C).

What is the average humidity in December in Boulder?

In December, the average relative humidity is 83%.

How much does it rain in Boulder in December?

In December, the rain falls for 7.2 days. Throughout December, 0.55" (14mm) of precipitation is accumulated.

How much does it snow in Boulder in December?

In Boulder, Wyoming, in December, during 13.5 snowfall days, 4.33" (110mm) of snow is typically accumulated.

What is the month with the shortest days in Boulder?

The month with the shortest days in Boulder, Wyoming, is December, with an average of 9h and 6min of daylight.

How many hours of daylight does Boulder have in December?

The average day length in December in Boulder, Wyoming, is 9h and 6min.

What time are sunrise and sunset in December in Boulder?

On the first day of December in Boulder, sunrise is at 7:30 am and sunset at 4:46 pm. On the last day of the month, sunrise is at 7:49 am and sunset at 4:55 pm MST.

How long on average sun shines in December in Boulder?

In Boulder, Wyoming, the average sunshine duration in December is 6.5h.

What is the month with the lowest UV index in Boulder?

January through April, October through December, with an average maximum UV index of 2, are months with the lowest UV index.

What is the UV index reading in December in Boulder?

In December, the average daily maximum UV index in Boulder, Wyoming, is 2. A UV Index estimate of 2, and below, represents a minimal hazard to health 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, WY

Average temperature in December - Boulder, WY
  • Average high temperature in December: 23.9°F

The warmest month (with the highest average high temperature) is July (78.4°F).
The month with the lowest average high temperature is December (23.9°F).

  • Average low temperature in December: 5.9°F

The month with the highest average low temperature is July (55.2°F).
The coldest month (with the lowest average low temperature) is January (5.4°F).

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Average pressure in December
Boulder, WY

Average pressure in December - Boulder, WY
  • Average pressure in December: 30.24"Hg

The month with the highest atmospheric pressure is January (30.27"Hg).
The month with the lowest atmospheric pressure is June (29.9"Hg).

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Average wind speed in December
Boulder, WY

Average wind speed in December - Boulder, WY
  • Average wind speed in December: 5.8mph

The windiest month (with the highest average wind speed) is June (8.1mph).
The calmest month (with the lowest average wind speed) is December (5.8mph).

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Average humidity in December
Boulder, WY

Average humidity in December - Boulder, WY
  • Average humidity in December: 83%

The month with the highest relative humidity is February (86%).
The month with the lowest relative humidity is August (34%).

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Average rainfall in December
Boulder, WY

Average rainfall in December - Boulder, WY
  • Average rainfall in December: 0.55"

The wettest month (with the highest rainfall) is May (1.73").
The driest month (with the least rainfall) is August (0.51").

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Average rainfall days in December
Boulder, WY

Average rainfall days in December - Boulder, WY
  • Average rainfall days in December: 7.2 days

The month with the highest number of rainy days is May (15.2 days).
The month with the least rainy days is January (5.5 days).

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Average snowfall in December
Boulder, WY

Average snowfall in December - Boulder, WY
  • Average snowfall in December: 4.33"

The month with the highest snowfall is February (7.32").
The months with the least snowfall are July and August (0").

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Average snowfall days in December
Boulder, WY

Average snowfall days in December - Boulder, WY
  • Average snowfall days in December: 13.5 days

The month with the highest number of snowfall days is March (15.7 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, WY

Average daylight in December / Average sunshine in December - Boulder, WY
  • Average daylight in December: 9h and 1min

The month with the longest days is June (Average daylight: 15h and 18min).
The month with the shortest days is December (Average daylight: 9h and 6min).

  • Average sunshine in December: 6h and 3min

The months with the most sunshine are July and August (Average sunshine: 11h and 54min).
The month with the least sunshine is January (Average sunshine: 6h and 18min).

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Average sunshine days in December
Boulder, WY

Average sunshine days in December - Boulder, WY
  • Average sunshine days in December: 16.7 days

The month with the most sunshine days is January (19.8 days).
The month with the least sunshine days is May (9.7 days).

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Average UV index in December
Boulder, WY

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

The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, March, April, October, November and December (UV index 2).

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Average cloud cover in December
Boulder, WY

Average cloud cover in December - Boulder, WY
  • Average cloud cover in December: 34

The month with the most cloud cover is February (Cloud cover 39).
The month with the least cloud cover is August (Cloud cover 11).

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Average visibility in December
Boulder, WY

Average visibility in December - Boulder, WY
  • 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 and February (4mi).

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Boulder, Wyoming, USA

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