December weather forecast
Custer, SD

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Large, scenic rocks and trees around this tiny Sylvan Lake located in the tranquil Custer State Park in Custer City, South Dakota
Large, scenic rocks and trees around this tiny Sylvan Lake located in the tranquil Custer State Park in Custer City, South Dakota

Weather in December

December in Custer indicates the solid arrival of winter, a stark contrast to the transitional weather of November. The city starts decking in white, courtesy of frequent and extended spells of snowfall. Peak winter sets in, with daily temperature ranges seldom climbing above the freezing point. The days grow shorter, a prelude to the solstice, ushering in a new year. In the midst of the chill, a white Christmas is almost always guaranteed, enhancing the festive atmosphere of this holiday season.

Temperature

In Custer, South Dakota, December records the lowest average temperatures, peaking at 29.8°F (-1.2°C) and reaching a low of 16.5°F (-8.6°C).

Humidity

In December, the average relative humidity is 74%.

Rainfall

In Custer, in December, during 6.3 rainfall days, 0.67" (17mm) of precipitation is typically accumulated. Throughout the year, in Custer, there are 135.4 rainfall days, and 20.39" (518mm) of precipitation is accumulated.

Snowfall

Months with snowfall are January through May, September through December. In December, in Custer, it is snowing for 11.5 days. Throughout December, 4.57" (116mm) of snow is accumulated. Throughout the year, in Custer, there are 75.1 snowfall days, and 40.24" (1022mm) of snow is accumulated.

Daylight

December has the shortest days of the year, with an average of 9h and 0min of daylight.
On the first day of the month, sunrise is at 7:09 am and sunset at 4:18 pm. On the last day of December, sunrise is at 7:28 am and sunset at 4:27 pm MST.

Sunshine

In Custer, the average sunshine in December is 6.2h.

UV index

The months with the lowest UV index are January through March, October through December, with an average maximum UV index of 2. A UV Index estimate of 2, and below, represents a minimal health hazard from unsafe exposure to UV radiation for ordinary individuals.
Note: The maximum UV index of 2 during December leads to these instructions:
Most people can stay in the Sun for up to 1 hour without burning, apart from children that always must be protected from sun exposure. The intensity of the Sun's UV radiation during midday suggests reducing time spent outdoors. During bright days, sunglasses that offer UVA and UVB defense are recommended. Attention! Nearly twice the Sun's UV radiation can be reflected by snow.
Updated: Feb 14, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What is the coldest time of year in Custer?

December, with its high-temperature average of 29.8°F (-1.2°C) and a low-temperature average of 16.5°F (-8.6°C), is the coldest month in Custer.

How cold is December in Custer?

The high-temperature, in December, in Custer, records 29.8°F (-1.2°C), while the low-temperature is 16.5°F (-8.6°C). The average heat index (a.k.a. 'felt air temperature', 'apparent temperature'), which represents the influence of relative humidity on air temperature, in July is appraised at 82.4°F (28°C).

What is the average humidity in December in Custer?

The average relative humidity in December is 74%.

How many days does it rain in December in Custer?

In December, in Custer, the rain falls for 6.3 days. Throughout December, 0.67" (17mm) of precipitation is accumulated.

How many days does it snow in December in Custer?

In December, in Custer, it is snowing for 11.5 days. Throughout December, 4.57" (116mm) of snow is accumulated.

What is the month with the shortest days in Custer?

December has the shortest days of the year, with an average of 9h and 0min of daylight.

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

The average day length in December in Custer, South Dakota, is 8h and 59min.

When is the sunrise / sunset in December in Custer?

In December, on the first day of the month, sunrise is at 7:09 am and sunset at 4:18 pm. On the last day of the month, in Custer, South Dakota, sunrise is at 7:28 am and sunset at 4:27 pm MST.

How long on average sun shines in December in Custer?

In December, the average sunshine duration in Custer is 6.2h.

What are the months with the lowest UV index in Custer?

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

How high is the UV index in December in Custer?

In Custer, South Dakota, the average daily maximum UV index in December is 2. A UV Index reading 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
Custer, SD

Average temperature in December - Custer, SD
  • Average high temperature in December: 29.8°F

The warmest month (with the highest average high temperature) is July (81.7°F).
The month with the lowest average high temperature is December (29.8°F).

  • Average low temperature in December: 16.5°F

The month with the highest average low temperature is July (60.4°F).
The coldest month (with the lowest average low temperature) is February (16.2°F).

Average pressure in December
Custer, SD

Average pressure in December - Custer, SD
  • Average pressure in December: 30.12"Hg

The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.84"Hg).

Average wind speed in December
Custer, SD

Average wind speed in December - Custer, SD
  • Average wind speed in December: 8.9mph

The windiest month (with the highest average wind speed) is April (9.5mph).
The calmest month (with the lowest average wind speed) is August (7mph).

Average humidity in December
Custer, SD

Average humidity in December - Custer, SD
  • Average humidity in December: 74%

The months with the highest relative humidity are January and February (77%).
The months with the lowest relative humidity are August and September (52%).

Average rainfall in December
Custer, SD

Average rainfall in December - Custer, SD
  • Average rainfall in December: 0.67"

The wettest month (with the highest rainfall) is June (3.19").
The driest month (with the least rainfall) is January (0.47").

Average rainfall days in December
Custer, SD

Average rainfall days in December - Custer, SD
  • Average rainfall days in December: 6.3 days

The month with the highest number of rainy days is May (18.6 days).
The month with the least rainy days is November (4.5 days).

Average snowfall in December
Custer, SD

Average snowfall in December - Custer, SD
  • Average snowfall in December: 4.57"

The month with the highest snowfall is April (7.24").
The months with the least snowfall are June, July and August (0").

Average snowfall days in December
Custer, SD

Average snowfall days in December - Custer, SD
  • Average snowfall days in December: 11.5 days

The month with the highest number of snowfall days is February (12.9 days).
The months with the least snowfall days are June, July and August (0 days).

Average daylight in December /
Average sunshine in December
Custer, SD

Average daylight in December / Average sunshine in December - Custer, SD
  • Average daylight in December: 9h and 0min

The month with the longest days is June (Average daylight: 15h and 24min).
The month with the shortest days is December (Average daylight: 9h and 0min).

  • Average sunshine in December: 6h and 1min

The month with the most sunshine is August (Average sunshine: 11h and 42min).
The month with the least sunshine is February (Average sunshine: 6h and 0min).

Average sunshine days in December
Custer, SD

Average sunshine days in December - Custer, SD
  • Average sunshine days in December: 18.1 days

The month with the most sunshine days is November (19.2 days).
The month with the least sunshine days is May (7.8 days).

Average UV index in December
Custer, SD

Average UV index in December - Custer, SD
  • 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, October, November and December (UV index 2).

Average cloud cover in December
Custer, SD

Average cloud cover in December - Custer, SD
  • Average cloud cover in December: 34

The month with the most cloud cover is April (Cloud cover 38).
The month with the least cloud cover is August (Cloud cover 17).

Average visibility in December
Custer, SD

Average visibility in December - Custer, SD
  • 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).

Custer, South Dakota, USA

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