December weather forecast
Casper, WY

The calm North Platte River flowing through downtown Casper in Wyoming
The calm North Platte River flowing through downtown Casper in Wyoming

Weather in December

December, the first month of the winter in Casper, is still a freezing cold month, with an average temperature ranging between min 15.1°F (-9.4°C) and max 28.4°F (-2°C).

Temperature

The coldest month is December, with an average high-temperature of 28.4°F (-2°C) and an average low-temperature of 15.1°F (-9.4°C).

Humidity

In December, the average relative humidity in Casper is 77%.

Rainfall

In December, in Casper, the rain falls for 4.1 days. Throughout December, 0.51" (13mm) of precipitation is accumulated. In Casper, during the entire year, the rain falls for 91.6 days and collects up to 9.69" (246mm) of precipitation.

Snowfall

Months with snowfall in Casper are January through May, September through December. In Casper, during December, snow falls for 9.9 days and regularly aggregates up to 3.7" (94mm) of snow. In Casper, during the entire year, snow falls for 61.5 days and aggregates up to 32.13" (816mm) of snow.

Daylight

December has the shortest days of the year in Casper, with an average of 9h and 5min of daylight.
On the first day of December in Casper, Wyoming, sunrise is at 7:16 am and sunset at 4:32 pm. On the last day of the month, sunrise is at 7:35 am and sunset at 4:40 pm MST.

Sunshine

The average sunshine in December is 6.4h.

UV index

January through April, October through December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index of 2, and less, symbolizes a low threat to health from exposure to the Sun's UV rays for ordinary individuals.
Note: The average daily UV index of 2 in December transform into the following instructions:
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. 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. 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 Casper?

With an average high-temperature of 28.4°F (-2°C) and an average low-temperature of 15.1°F (-9.4°C), December is the coldest month in Casper, Wyoming.

What is the temperature in December in Casper?

In Casper, Wyoming, in December, the average high-temperature is 28.4°F (-2°C), and the average low-temperature is 15.1°F (-9.4°C).

What is the average humidity in December in Casper?

The average relative humidity in December in Casper, Wyoming, is 77%.

How much does it rain in Casper in December?

In Casper, Wyoming, during December, the rain falls for 4.1 days and regularly aggregates up to 0.51" (13mm) of precipitation.

How much does it snow in Casper in December?

In Casper, during December, snow falls for 9.9 days and regularly aggregates up to 3.7" (94mm) of snow.

What is the month with the shortest days in Casper?

December has the shortest days of the year in Casper, Wyoming, with an average of 9h and 5min of daylight.

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

The average day length in December in Casper is 9h and 5min.

What time are sunrise and sunset in December in Casper?

In December, on the first day of the month, sunrise is at 7:16 am and sunset at 4:32 pm. On the last day of the month, sunrise is at 7:35 am and sunset at 4:40 pm MST.

How many hours of sunshine does Casper have in December?

The average sunshine duration in December in Casper is 6.4h.

When is the lowest UV index in Casper?

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

What is the UV index reading in December in Casper?

The average daily maximum UV index in December in Casper is 2. A UV Index value of 2, and less, symbolizes a low health threat 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
Casper, WY

Average temperature in December - Casper, WY
  • Average high temperature in December: 28.4°F

The warmest month (with the highest average high temperature) is July (83.5°F).
The month with the lowest average high temperature is December (28.4°F).

  • Average low temperature in December: 15.1°F

The month with the highest average low temperature is July (59.5°F).
The coldest month (with the lowest average low temperature) is December (15.1°F).

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Average pressure in December
Casper, WY

Average pressure in December - Casper, WY
  • Average pressure in December: 30.15"Hg

The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.85"Hg).

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Average wind speed in December
Casper, WY

Average wind speed in December - Casper, WY
  • Average wind speed in December: 11.7mph

The windiest month (with the highest average wind speed) is January (12.1mph).
The calmest months (with the lowest average wind speed) are July and August (8.5mph).

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Average humidity in December
Casper, WY

Average humidity in December - Casper, WY
  • Average humidity in December: 77%

The month with the highest relative humidity is January (79%).
The month with the lowest relative humidity is August (37%).

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Average rainfall in December
Casper, WY

Average rainfall in December - Casper, WY
  • Average rainfall in December: 0.51"

The wettest month (with the highest rainfall) is May (1.77").
The driest months (with the least rainfall) are January, August and September (0.43").

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Average rainfall days in December
Casper, WY

Average rainfall days in December - Casper, WY
  • Average rainfall days in December: 4.1 days

The month with the highest number of rainy days is May (14.1 days).
The month with the least rainy days is January (3.6 days).

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Average snowfall in December
Casper, WY

Average snowfall in December - Casper, WY
  • Average snowfall in December: 3.7"

The month with the highest snowfall is November (5.47").
The months with the least snowfall are June, July and August (0").

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Average snowfall days in December
Casper, WY

Average snowfall days in December - Casper, WY
  • Average snowfall days in December: 9.9 days

The month with the highest number of snowfall days is February (11.2 days).
The months with the least snowfall days are June, July and August (0 days).

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Average daylight in December /
Average sunshine in December
Casper, WY

Average daylight in December / Average sunshine in December - Casper, WY
  • Average daylight in December: 9h and 5min

The month with the longest days is June (Average daylight: 15h and 17min).
The month with the shortest days is December (Average daylight: 9h and 5min).

  • Average sunshine in December: 6h and 24min

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

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Average sunshine days in December
Casper, WY

Average sunshine days in December - Casper, WY
  • Average sunshine days in December: 20.5 days

The month with the most sunshine days is December (20.5 days).
The month with the least sunshine days is May (11.9 days).

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Average UV index in December
Casper, WY

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

The months with the highest UV index are June, July and August (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
Casper, WY

Average cloud cover in December - Casper, WY
  • Average cloud cover in December: 32

The month with the most cloud cover is February (Cloud cover 36).
The month with the least cloud cover is August (Cloud cover 13).

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Average visibility in December
Casper, WY

Average visibility in December - Casper, WY
  • Average visibility in December: 6mi

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

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