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

In Rapid City, the month of December is known for its lowest average temperatures, reaching a high of 32.5°F (0.3°C) and a low of 18.7°F (-7.4°C).

Humidity

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

Rainfall

In Rapid City, during December, the rain falls for 4.8 days and regularly aggregates up to 0.63" (16mm) of precipitation. Throughout the year, in Rapid City, there are 118.8 rainfall days, and 15.39" (391mm) of precipitation is accumulated.

Snowfall

January through May, September through December are months with snowfall in Rapid City. In Rapid City, during December, snow falls for 8.1 days and regularly aggregates up to 2.64" (67mm) of snow. Throughout the year, in Rapid City, there are 50.4 snowfall days, and 24.41" (620mm) of snow is accumulated.

Daylight

The month with the shortest days in Rapid City is December, 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

The months with the lowest UV index are January, February, November and December, with an average maximum UV index of 2. A UV Index estimate of 2, and below, represents a minimal health vulnerability from unprotected exposure to Sun's UV rays for the ordinary person.
Note: The maximum daily UV index of 2 during December translates into the following directions:
Children necessitate constant protection from sunlight, unlike the majority, who can remain under the sun for about an hour without burning. Being in direct Sun during midday can be harmful due to intense solar radiation; take precautions. A wide-brimmed hat is a shield, deflecting up to 50% of harmful UV radiation from eyes. Note this! The Sun's UV radiation can nearly be doubled by the reflection off snow.
Updated: Feb 14, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What part of the year is the coldest in Rapid City?

With average high temperatures of 32.5°F (0.3°C) and lows of 18.7°F (-7.4°C), December is the coldest month in Rapid City, South Dakota.

How cold is it in Rapid City in December?

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

What is the average humidity in December in Rapid City?

The average relative humidity in December in Rapid City is 74%.

How many days does it rain in December in Rapid City?

In Rapid City, in December, during 4.8 rainfall days, 0.63" (16mm) of precipitation is typically accumulated.

How many days does it snow in December in Rapid City?

In December, it is snowing for 8.1 days. Throughout December, 2.64" (67mm) of snow is accumulated.

What is the month with the shortest days in Rapid City?

The month with the shortest days in Rapid City, South Dakota, is December, with an average of 8h and 54min of daylight.

What is the average length of the day in December in Rapid City?

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

What time are sunrise and sunset in December in Rapid City?

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, in Rapid City, sunrise is at 7:27 am and sunset at 4:24 pm MST.

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

The average sunshine duration in December in Rapid City is 6h.

What is the month with the lowest UV index in Rapid City?

January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index in Rapid City, South Dakota.

How high is the UV index in December in Rapid City?

In December, the average daily maximum UV index in Rapid City, South Dakota, is 2. A UV Index estimate of 2, and below, represents a low health threat from exposure to the Sun's 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
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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