August 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 August

August continues the summer trend in Rapid City, South Dakota. Although temperatures start to cool down a notch, the heat persists, keeping the ambiance summery. It's one of the months with the least cloud cover, maximizing visibility, and promoting extended hours of sunshine. Rainfall does not vary significantly from that in July, suggesting consistent weather patterns. However, slightly shorter daylight hours hint at the approaching autumn.

Temperature

With the arrival of August, Rapid City's average high-temperature registers at a still warm 82.8°F (28.2°C), indicating a subtle variation from the previous month. August sees the temperature falling to a mean low of 61.5°F (16.4°C).

Heat index

For most parts of August, the heat index is appraised at 84.2°F (29°C). Long-standing exposure coupled with ongoing activity could result in exhaustion, possibly causing heat cramps.
Take into consideration that the heat index values are calculated for shade and light wind conditions. Direct sunlight can potentially boost the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'apparent temperature', is a calculated temperature value of how hot it feels when the moisture in the air is factored in. Elements such as metabolic variations, being pregnant, and physical activity can impact one's weather perception. Take note that direct exposure to the sun can increase the felt temperature, possibly adding 15 Fahrenheit (8 Celsius) degrees to the heat index. Heat index values hold particular importance for children. Young ones often disregard the necessity to rest and hydrate. Thirst usually indicates advanced dehydration - hence, it is key to stay hydrated, particularly during ongoing physical activities.

Humidity

August and September, with an average relative humidity of 50%, are the least humid months.

Rainfall

In Rapid City, in August, during 12.8 rainfall days, 1.5" (38mm) of precipitation is typically accumulated. In Rapid City, during the entire year, the rain falls for 118.8 days and collects up to 15.39" (391mm) of precipitation.

Snowfall

June through August are months without snowfall.

Daylight

In August, the average length of the day in Rapid City is 13h and 57min.
On the first day of August, sunrise is at 5:41 am and sunset at 8:16 pm. On the last day of the month, sunrise is at 6:15 am and sunset at 7:30 pm MDT.

Sunshine

The month with the most sunshine in Rapid City is August, with an average of 11.8h of sunshine.

UV index

In Rapid City, the average daily maximum UV index in August is 5. A UV Index value of 3 to 5 symbolizes a moderate threat to health from unprotected exposure to Sun's UV rays for the ordinary person.
Note: A maximum daily UV index of 5 during August morphs into the following directions:
Be vigilant - Preventing sunburn is recommended. The Sun's UV radiation is especially harmful around midday, so reduce exposure and stay safe. A hat with a generous brim can prevent nearly 50% of UV rays from reaching your eyes.
Updated: Aug 19, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

How hot is it in August?

In August, in Rapid City, the average high-temperature is 82.8°F (28.2°C), and the average low-temperature is 61.5°F (16.4°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 are the least humid months?

The months with the lowest humidity are August and September, with an average relative humidity of 50%.

What is the average humidity in August?

The average relative humidity in August in Rapid City is 50%.

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

In Rapid City, in August, during 12.8 rainfall days, 1.5" (38mm) of precipitation is typically accumulated.

When it does not snow in Rapid City?

June through August are months without snowfall.

Does it snow in August?

In Rapid City, in August, it doesn't snow. In September, it regularly snows.

How many hours of daylight does Rapid City have in August?

In August, the average day length is 13h and 57min.

When is the sunrise / sunset in August?

On the first day of August, sunrise is at 5:41 am and sunset at 8:16 pm. On the last day of the month, sunrise is at 6:15 am and sunset at 7:30 pm MDT.

What month has the most sunshine in Rapid City?

With an average of 11.8h of sunshine, August has the most sunshine of the year.

How long on average sun shines in August?

The average sunshine duration in August is 11.8h.

How high is the UV index in August?

The average daily maximum UV index in August is 5. A UV Index estimate of 3 to 5 represents a moderate health threat from exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in August
Rapid City, SD

Average temperature in August - Rapid City, SD
  • Average high temperature in August: 82.8°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 August: 61.5°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 August
Rapid City, SD

Average pressure in August - Rapid City, SD
  • Average pressure in August: 29.9"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 August
Rapid City, SD

Average wind speed in August - Rapid City, SD
  • Average wind speed in August: 8.2mph

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 August
Rapid City, SD

Average humidity in August - Rapid City, SD
  • Average humidity in August: 50%

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 August
Rapid City, SD

Average rainfall in August - Rapid City, SD
  • Average rainfall in August: 1.5"

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 August
Rapid City, SD

Average rainfall days in August - Rapid City, SD
  • Average rainfall days in August: 12.8 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 August
Rapid City, SD

Average snowfall in August - Rapid City, SD
  • Average snowfall in August: 0"

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 August
Rapid City, SD

Average snowfall days in August - Rapid City, SD
  • Average snowfall days in August: 0 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 August /
Average sunshine in August
Rapid City, SD

Average daylight in August / Average sunshine in August - Rapid City, SD
  • Average daylight in August: 14h 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: 8h and 54min).

  • Average sunshine in August: 11h and 5min

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 August
Rapid City, SD

Average sunshine days in August - Rapid City, SD
  • Average sunshine days in August: 14.5 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 August
Rapid City, SD

Average UV index in August - Rapid City, SD
  • Average UV index in August: 5

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 August
Rapid City, SD

Average cloud cover in August - Rapid City, SD
  • Average cloud cover in August: 16

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 August
Rapid City, SD

Average visibility in August - Rapid City, SD
  • Average visibility in August: 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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