Average Weather in Rapid City South Dakota, United States
In Rapid City, the summers are warm and mostly clear and the winters are freezing, dry, windy, and partly cloudy. Over the course of the year, the temperature typically varies from 17°F to 87°F and is rarely below -3°F or above 98°F.
The hot season lasts for 3.1 months, from June 13 to September 15, with an average daily high temperature above 76°F. The hottest day of the year is July 27, with an average high of 87°F and low of 62°F.
The cold season lasts for 3.6 months, from November 19 to March 7, with an average daily high temperature below 46°F. The coldest day of the year is January 1, with an average low of 17°F and high of 35°F.
Average High and Low Temperature
The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, 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 Rapid City, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.
The clearer part of the year in Rapid City begins around June 8 and lasts for 4.1 months, ending around October 11. On July 4, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 76% of the time, and overcast or mostly cloudy 24% of the time.
The cloudier part of the year begins around October 11 and lasts for 7.9 months, ending around June 8. On March 27, the cloudiest day of the year, the sky is overcast or mostly cloudy 52% of the time, and clear, mostly clear, or partly cloudy 48% of the time.
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Rapid City varies significantly throughout the year.
The wetter season lasts 3.9 months, from April 21 to August 19, with a greater than 20% chance of a given day being a wet day. The chance of a wet day peaks at 37% on June 6.
The drier season lasts 8.1 months, from August 19 to April 21. The smallest chance of a wet day is 3% on January 15.
Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation in Rapid City changes throughout the year.
Rain alone is the most common for 8.1 months, from March 11 to November 14. The highest chance of a day with rain alone is 37% on June 6.
Snow alone is the most common for 3.8 months, from November 14 to March 11. The highest chance of a day with snow alone is 4% on December 2.
Daily Chance of Precipitation
To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Rapid City experiences significant seasonal variation in monthly rainfall.
The rainy period of the year lasts for 7.1 months, from March 28 to November 1, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around May 25, with an average total accumulation of 2.7 inches.
The rainless period of the year lasts for 4.9 months, from November 1 to March 28. The least rain falls around December 27, with and average total accumulation of 0.0 inches.
Average Monthly Rainfall
We report snowfall in liquid-equivalent terms. The actual depth of new snowfall is typically between 5 and 10 times the liquid-equivalent amount, assuming the ground is frozen. Colder, drier snow tends to be on the higher end of that range and warmer, wetter snow on the lower end.
As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Rapid City experiences some seasonal variation in monthly liquid-equivalent snowfall.
The snowy period of the year lasts for 6.5 months, from October 26 to May 11, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around April 4, with an average total liquid-equivalent accumulation of 0.3 inches.
The snowless period of the year lasts for 5.5 months, from May 11 to October 26. The least snow falls around July 21, with an average total liquid-equivalent accumulation of 0.0 inches.
Average Liquid-Equivalent Monthly Snowfall
The length of the day in Rapid City varies significantly over the course of the year. In 2017, the shortest day is December 21, with 8 hours, 53 minutes of daylight; the longest day is June 21, with 15 hours, 30 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:09 AM on June 14, and the latest sunrise is 2 hours, 25 minutes later at 7:33 AM on November 4. The earliest sunset is at 4:14 PM on December 9, and the latest sunset is 4 hours, 26 minutes later at 8:40 PM on June 26.
Daylight saving time (DST) is observed in Rapid City during 2017, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.
Sunrise & Sunset with Twilight and Daylight Saving Time
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 perceived humidity level in Rapid City, as measured by the percentage of time in which the humidity comfort level is muggy, oppressive, or miserable, does not vary significantly over the course of the year, staying within 1% of 1% throughout.
Humidity Comfort Levels
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 experiences mild seasonal variation over the course of the year.
The windier part of the year lasts for 8.2 months, from September 25 to June 1, with average wind speeds of more than 4.8 miles per hour. The windiest day of the year is January 18, with an average hourly wind speed of 5.5 miles per hour.
The calmer time of year lasts for 3.8 months, from June 1 to September 25. The calmest day of the year is July 30, with an average hourly wind speed of 4.1 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Rapid City varies throughout the year.
The wind is most often from the north for 2.9 months, from March 27 to June 23 and for 2.3 weeks, from September 3 to September 19, with a peak percentage of 35% on April 13. The wind is most often from the south for 2.3 months, from June 23 to September 3, with a peak percentage of 33% on August 16. The wind is most often from the west for 6.3 months, from September 19 to March 27, with a peak percentage of 60% on January 1.
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 experiences extreme seasonal variation over the course of the year.
The brighter period of the year lasts for 3.2 months, from May 10 to August 17, with an average daily incident shortwave energy per square meter above 6.5 kWh. The brightest day of the year is July 3, with an average of 7.7 kWh.
The darker period of the year lasts for 3.5 months, from October 29 to February 13, with an average daily incident shortwave energy per square meter below 3.0 kWh. The darkest day of the year is December 21, with an average of 1.8 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Rapid City are 44.081 deg latitude, -103.231 deg longitude, and 3,330 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: Ellsworth Air Force Base (52%, 13 kilometers, northeast); Rapid City Regional Airport (40%, 15 kilometers, east); Custer County Airfield (3.2%, 49 kilometers, southwest); and Black Hills Airport (4.7%, 63 kilometers, northwest).
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , 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 aiports and weather stations are provided by AskGeo.com .
Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.