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August Weather in Rapid City South Dakota, United States

Daily high temperatures decrease by 4°F, from 87°F to 82°F, rarely falling below 70°F or exceeding 96°F.

Daily low temperatures decrease by 5°F, from 61°F to 56°F, rarely falling below 47°F or exceeding 68°F.

For reference, on July 26, the hottest day of the year, temperatures in Rapid City typically range from 62°F to 87°F, while on January 1, the coldest day of the year, they range from 17°F to 35°F.

Average High and Low Temperature in August in Rapid City

The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.

The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on August. The horizontal axis is the day, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.

Average Hourly Temperature in August in Rapid City

Average Hourly Temperature in August in Rapid CityAug112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030313112 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AMJulSepcoldcoldcoolcoolcomfortablecomfortablewarm
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The average hourly temperature, color coded into bands. The shaded overlays indicate night and civil twilight.

Kuluncak, Turkey (6,215 miles away) is the far-away foreign place with temperatures most similar to Rapid City (view comparison).

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The month of August in Rapid City experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 27% throughout the month.

The clearest day of the month is August 20, with clear, mostly clear, or partly cloudy conditions 75% of the time.

For reference, on March 26, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 52%, while on July 3, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 76%.

Cloud Cover Categories in August in Rapid City

Cloud Cover Categories in August in Rapid CityAug11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%JulSepAug 175%Aug 175%Aug 3171%Aug 3171%Aug 1174%Aug 1174%Aug 2174%Aug 2174%clearmostly clearpartly cloudymostly cloudyovercast
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Rapid City, the chance of a wet day over the course of August is very rapidly decreasing, starting the month at 28% and ending it at 16%.

For reference, the year's highest daily chance of a wet day is 37% on June 5, and its lowest chance is 3% on January 16.

Probability of Precipitation in August in Rapid City

The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).

Rainfall

To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day.

The average sliding 31-day rainfall during August in Rapid City is gradually decreasing, starting the month at 1.5 inches, when it rarely exceeds 2.5 inches or falls below 0.7 inches, and ending the month at 1.1 inches, when it rarely exceeds 2.0 inches or falls below 0.3 inches.

Average Monthly Rainfall in August in Rapid City

The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average snowfall.

Over the course of August in Rapid City, the length of the day is rapidly decreasing. From the start to the end of the month, the length of the day decreases by 1 hour, 21 minutes, implying an average daily decrease of 2 minutes, 41 seconds, and weekly decrease of 18 minutes, 50 seconds.

The shortest day of the month is August 31, with 13 hours, 14 minutes of daylight and the longest day is August 1, with 14 hours, 35 minutes of daylight.

Hours of Daylight and Twilight in August in Rapid City

The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

The earliest sunrise of the month in Rapid City is 5:41 AM on August 1 and the latest sunrise is 34 minutes later at 6:15 AM on August 31.

The latest sunset is 8:16 PM on August 1 and the earliest sunset is 47 minutes earlier at 7:29 PM on August 31.

Daylight saving time is observed in Rapid City during 2024, but it neither starts nor ends during August, so the entire month is in standard time.

For reference, on June 20, the longest day of the year, the Sun rises at 5:09 AM and sets 15 hours, 30 minutes later, at 8:39 PM, while on December 21, the shortest day of the year, it rises at 7:25 AM and sets 8 hours, 53 minutes later, at 4:17 PM.

Sunrise & Sunset with Twilight in August in Rapid City

The solar day over the course of August. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray.

The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation.

Solar Elevation and Azimuth in August in Rapid City

Solar Elevation and Azimuth in August in Rapid CityAug112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030313112 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AMJulSep00101020202030304040505060000101020203030304040505060
northeastsouthwest
Solar elevation and azimuth over the course of August 2024. The black lines are lines of constant solar elevation (the angle of the sun above the horizon, in degrees). The background color fills indicate the azimuth (the compass bearing) of the sun. The lightly tinted areas at the boundaries of the cardinal compass points indicate the implied intermediate directions (northeast, southeast, southwest, and northwest).

The figure below presents a compact representation of key lunar data for August 2024. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases. The label associated with each bar indicates the date and time that the phase is obtained, and the companion time labels indicate the rise and set times of the Moon for the nearest time interval in which the moon is above the horizon.

Moon Rise, Set & Phases in August in Rapid City

Moon Rise, Set & Phases in August in Rapid CityAug112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030313112 AM12 AM4 AM4 AM8 AM8 AM12 PM12 PM4 PM4 PM8 PM8 PM12 AM12 AMJulSepJul 54:58 PMJul 54:58 PMJul 214:18 AMJul 214:18 AMAug 45:14 AMAug 45:14 AMAug 1912:26 PMAug 1912:26 PMSep 27:56 PMSep 27:56 PMSep 178:35 PMSep 178:35 PM4:26 AM4:26 AM9:09 PM9:09 PM8:38 PM8:38 PM5:19 AM5:19 AM5:37 AM5:37 AM8:47 PM8:47 PM7:44 PM7:44 PM5:36 AM5:36 AM5:41 AM5:41 AM7:32 PM7:32 PM6:57 PM6:57 PM7:12 AM7:12 AM
The time in which the moon is above the horizon (light blue area), with new moons (dark gray lines) and full moons (blue lines) indicated. The shaded overlays indicate night and civil twilight.
Aug 2024IlluminationMoonriseMoonsetMoonriseMeridian PassingDistance
1
8%2:16 AMNE7:05 PMNW-10:42 AMS240,871 mi
2
3%3:19 AMNE7:48 PMNW-11:37 AMS243,085 mi
3
1%4:27 AMNE8:21 PMWNW-12:29 PMS245,220 mi
4
0%5:37 AMENE8:47 PMWNW-1:17 PMS247,214 mi
5
2%6:45 AMENE9:08 PMWNW-2:01 PMS248,983 mi
6
5%7:51 AMENE9:26 PMW-2:42 PMS250,422 mi
7
11%8:55 AME9:43 PMW-3:21 PMS251,411 mi
8
17%9:58 AME9:59 PMW-4:00 PMS251,832 mi
9
25%11:00 AME10:15 PMWSW-4:39 PMS251,578 mi
10
34%12:03 PMESE10:33 PMWSW-5:19 PMS250,572 mi
11
44%1:08 PMESE10:55 PMWSW-6:02 PMS248,782 mi
12
50%2:16 PMESE11:22 PMWSW-6:49 PMS246,237 mi
13
64%3:25 PMSE11:56 PMSW-7:41 PMS243,036 mi
14
74%4:32 PMSE--8:37 PMS239,359 mi
15
83%-12:42 AMSW5:35 PMSE9:38 PMS235,465 mi
16
91%-1:41 AMSW6:28 PMSE10:40 PMS231,676 mi
17
97%-2:52 AMSW7:10 PMSE11:41 PMS228,342 mi
18
98%-4:12 AMWSW7:44 PMESE--
19
100%-5:36 AMWSW8:11 PMESE12:39 AMS225,784 mi
20
100%-6:59 AMWSW8:35 PME1:34 AMS224,240 mi
21
96%-8:20 AMW8:56 PME2:26 AMS223,823 mi
22
90%-9:41 AMW9:17 PME3:15 AMS224,513 mi
23
82%-11:01 AMWNW9:40 PMENE4:05 AMS226,165 mi
24
71%-12:21 PMWNW10:07 PMENE4:55 AMS228,551 mi
25
60%-1:41 PMWNW10:39 PMNE5:48 AMS231,407 mi
26
50%-2:57 PMNW11:20 PMNE6:43 AMS234,479 mi
27
37%-4:06 PMNW-7:40 AMS237,551 mi
28
27%12:11 AMNE5:03 PMNW-8:38 AMS240,469 mi
29
18%1:11 AMNE5:49 PMNW-9:33 AMS243,133 mi
30
11%2:17 AMNE6:24 PMNW-10:26 AMS245,495 mi
31
5%3:26 AMENE6:52 PMWNW-11:14 AMS247,536 mi

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

The chance that a given day will be muggy in Rapid City is essentially constant during August, remaining within 1% of 1% throughout.

For reference, on July 18, the muggiest day of the year, there are muggy conditions 3% of the time, while on September 24, the least muggy day of the year, there are muggy conditions 0% of the time.

Humidity Comfort Levels in August in Rapid City

Humidity Comfort Levels in August in Rapid CityAug11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%JulSepAug 12%Aug 12%Aug 311%Aug 311%Aug 111%Aug 111%Aug 211%Aug 211%humidhumidcomfortablecomfortabledrydrymuggymuggy
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The percentage of time spent at various humidity comfort levels, categorized by dew point.

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in Rapid City is essentially constant during August, remaining within 0.2 miles per hour of 7.8 miles per hour throughout.

For reference, on January 18, the windiest day of the year, the daily average wind speed is 10.2 miles per hour, while on July 29, the calmest day of the year, the daily average wind speed is 7.7 miles per hour.

Average Wind Speed in August in Rapid City

The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

The hourly average wind direction in Rapid City throughout August is predominantly from the south, with a peak proportion of 33% on August 15.

Wind Direction in August in Rapid City

Wind Direction in August in Rapid CitySNWAug11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%20%80%40%60%60%40%80%20%100%0%JulSepwestsoutheastnorth
northeastsouthwest
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions, excluding hours in which the mean wind speed is less than 1.0 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

The growing season in Rapid City typically lasts for 5.0 months (153 days), from around May 4 to around October 4, rarely starting before April 14 or after May 22, and rarely ending before September 13 or after October 23.

The month of August in Rapid City is reliably fully within the growing season.

Time Spent in Various Temperature Bands and the Growing Season in August in Rapid City

Time Spent in Various Temperature Bands and the Growing Season in August in Rapid Citygrowing seasonAug11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%JulSep100%Aug 16100%Aug 1690%Sep 1390%Sep 13Jul 19100%Jul 19100%very coldcoldcoolcomfortablewarmhot
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The percentage of time spent in various temperature bands. The black line is the percentage chance that a given day is within the growing season.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

The average accumulated growing degree days in Rapid City are rapidly increasing during August, increasing by 620°F, from 1,562°F to 2,182°F, over the course of the month.

Growing Degree Days in August in Rapid City

The average growing degree days accumulated over the course of August, with 25th to 75th and 10th to 90th percentile bands.

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy in Rapid City is decreasing during August, falling by 1.0 kWh, from 7.0 kWh to 5.9 kWh, over the course of the month.

Average Daily Incident Shortwave Solar Energy in August in Rapid City

Average Daily Incident Shortwave Solar Energy in August in Rapid CityAug11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310 kWh0 kWh1 kWh1 kWh2 kWh2 kWh3 kWh3 kWh4 kWh4 kWh5 kWh5 kWh6 kWh6 kWh7 kWh7 kWh8 kWh8 kWh9 kWh9 kWhJulSepAug 17.0 kWhAug 17.0 kWhAug 315.9 kWhAug 315.9 kWhAug 116.7 kWhAug 116.7 kWhAug 216.3 kWhAug 216.3 kWh
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

For the purposes of this report, the geographical coordinates of Rapid City are 44.081 deg latitude, -103.231 deg longitude, and 3,238 ft elevation.

The topography within 2 miles of Rapid City contains significant variations in elevation, with a maximum elevation change of 689 feet and an average elevation above sea level of 3,334 feet. Within 10 miles contains significant variations in elevation (1,991 feet). Within 50 miles contains large variations in elevation (5,135 feet).

The area within 2 miles of Rapid City is covered by artificial surfaces (59%) and grassland (35%), within 10 miles by grassland (67%) and trees (18%), and within 50 miles by grassland (61%) and trees (23%).

This report illustrates the typical weather in Rapid City, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.

Temperature and Dew Point

There are 4 weather stations near enough to contribute to our estimation of the temperature and dew point in Rapid City.

For each station, the records are corrected for the elevation difference between that station and Rapid City according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.

The estimated value at Rapid City is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Rapid City and a given station.

The stations contributing to this reconstruction are:

To get a sense of how much these sources agree with each other, you can view a comparison of Rapid City and the stations that contribute to our estimates of its temperature history and climate. Please note that each source's contribution is adjusted for elevation and the relative change present in the MERRA-2 data.

Other Data

All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , by Jean Meeus.

All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.

Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.

Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.

Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .

Time zones for airports and weather stations are provided by AskGeo.com .

Maps are © OpenStreetMap contributors.

Disclaimer

The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.

We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.

We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.

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