December weather forecast
Rapid City, SD

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A scenic panorama of the Rapid City in South Dakota
A scenic panorama of the Rapid City in South Dakota

Weather in December

December in Rapid City, South Dakota culminates in full-blown winter weather. An average temperature low at around 18.7°F (-7.4°C) suggests the harshness of the season. Snowfall, combined with a decrease in daylight hours, creates quintessential cozy winter days. The holiday atmosphere complements the weather beautifully. Significantly higher humidity and persistent easterly winds further highlight the classic manifestation of winter in the region.

Temperature

December, noted for its average high-temperature of 32.5°F (0.3°C) and an average low-temperature of 18.7°F (-7.4°C), is considered the coldest month.

Humidity

The average relative humidity in December is 74%.

Rainfall

In Rapid City, in December, it is raining for 4.8 days, with typically 0.63" (16mm) of accumulated precipitation. In Rapid City, during the entire year, the rain falls for 118.8 days and collects up to 15.39" (391mm) of precipitation.

Snowfall

Months with snowfall are January through May, September through December. In Rapid City, in December, during 8.1 snowfall days, 2.64" (67mm) of snow is typically accumulated. Throughout the year, there are 50.4 snowfall days, and 24.41" (620mm) of snow is accumulated.

Daylight

December has the shortest days of the year, with an average of 8h and 54min of daylight.
On the first day of December, sunrise is at 7:08 am and sunset at 4:15 pm. On the last day of the month, sunrise is at 7:27 am and sunset at 4:24 pm MST.

Sunshine

In December, the average sunshine is 6h.

UV index

January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index in Rapid City. A UV Index of 2, and less, symbolizes a minimal health vulnerability from unprotected exposure to Sun's UV rays for ordinary individuals.
Note: The UV index of 2 in December translates into these instructions:
Though extended exposure to the sun typically does not concern most people, it is crucial to always shield children, infants, and those with sensitive skin. To avoid the Sun's strongest rays, limit exposure around the mid-day period. A wide-brimmed hat is a staple for defending the face, eyes, ears, and neck from the Sun. Attention! Nearly twice the Sun's UV radiation can be reflected by snow.
Updated: Aug 19, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What month is the coldest?

The month of December sees the average lowest temperatures, reaching 32.5°F (0.3°C) at the peak and 18.7°F (-7.4°C) at the low.

How cold is it in December?

The high-temperature, in December, in Rapid City, is 32.5°F (0.3°C), while the low-temperature averages to 18.7°F (-7.4°C). The average heat index (a.k.a. 'apparent temperature', 'feels like'), which combines relative humidity and air temperature, in August is appraised at 84.2°F (29°C).

What is the average humidity in December in Rapid City?

In Rapid City, the average relative humidity in December is 74%.

How much does it rain in December?

In Rapid City, in December, it is raining for 4.8 days, with typically 0.63" (16mm) of accumulated precipitation.

How many days does it snow in December?

In Rapid City, in December, snow falls for 8.1 days, with typically accumulated 2.64" (67mm) of snow.

What is the month with the shortest days?

With an average of 8h and 54min of daylight, December has the shortest days of the year in Rapid City.

What is the average length of the day in December?

In Rapid City, the average day length in December is 8h and 57min.

When are sunrise and sunset in December?

In December, on the first day of the month, sunrise is at 7:08 am and sunset at 4:15 pm. On the last day of the month, sunrise is at 7:27 am and sunset at 4:24 pm MST.

How many hours of sunshine does Rapid City have in December?

In December, the average sunshine duration is 6h.

What is the month with the lowest UV index?

The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 2.

How high is the UV index in December?

In Rapid City, the average daily maximum UV index in December is 2. A UV Index of 2, and less, symbolizes a low health threat from unsafe exposure to Sun's UV rays.
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
Rapid City, SD

Average temperature in December - Rapid City, SD
  • Average high temperature in December: 32.5°F

The warmest month (with the highest average high temperature) is July (84.7°F).
The month with the lowest average high temperature is December (32.5°F).

  • Average low temperature in December: 18.7°F

The month with the highest average low temperature is July (63.3°F).
The coldest month (with the lowest average low temperature) is February (17.8°F).

Average pressure in December
Rapid City, SD

Average pressure in December - Rapid City, SD
  • Average pressure in December: 30.13"Hg

The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.84"Hg).

Average wind speed in December
Rapid City, SD

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

The windiest month (with the highest average wind speed) is April (10.3mph).
The calmest month (with the lowest average wind speed) is August (8.2mph).

Average humidity in December
Rapid City, SD

Average humidity in December - Rapid City, SD
  • Average humidity in December: 74%

The month with the highest relative humidity is January (77%).
The months with the lowest relative humidity are August and September (50%).

Average rainfall in December
Rapid City, SD

Average rainfall in December - Rapid City, SD
  • Average rainfall in December: 0.63"

The wettest month (with the highest rainfall) is May (2.28").
The driest month (with the least rainfall) is January (0.43").

Average rainfall days in December
Rapid City, SD

Average rainfall days in December - Rapid City, SD
  • Average rainfall days in December: 4.8 days

The month with the highest number of rainy days is May (17.1 days).
The month with the least rainy days is December (4.8 days).

Average snowfall in December
Rapid City, SD

Average snowfall in December - Rapid City, SD
  • Average snowfall in December: 2.64"

The month with the highest snowfall is April (5.43").
The months with the least snowfall are June, July and August (0").

Average snowfall days in December
Rapid City, SD

Average snowfall days in December - Rapid City, SD
  • Average snowfall days in December: 8.1 days

The month with the highest number of snowfall days is February (10.5 days).
The months with the least snowfall days are June, July and August (0 days).

Average daylight in December /
Average sunshine in December
Rapid City, SD

Average daylight in December / Average sunshine in December - Rapid City, SD
  • Average daylight in December: 8h and 5min

The month with the longest days is June (Average daylight: 15h and 24min).
The month with the shortest days is December (Average daylight: 8h and 54min).

  • Average sunshine in December: 6h and 0min

The month with the most sunshine is August (Average sunshine: 11h and 48min).
The month with the least sunshine is February (Average sunshine: 5h and 54min).

Average sunshine days in December
Rapid City, SD

Average sunshine days in December - Rapid City, SD
  • Average sunshine days in December: 19.6 days

The month with the most sunshine days is November (20.2 days).
The month with the least sunshine days is May (11 days).

Average UV index in December
Rapid City, SD

Average UV index in December - Rapid City, SD
  • Average UV index in December: 2

The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).

Average cloud cover in December
Rapid City, SD

Average cloud cover in December - Rapid City, SD
  • Average cloud cover in December: 36

The months with the most cloud cover are February and April (Cloud cover 38).
The month with the least cloud cover is August (Cloud cover 16).

Average visibility in December
Rapid City, SD

Average visibility in December - Rapid City, 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).

Rapid City, South Dakota, USA

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