Summer Weather in Rapid City United States

Daily high temperatures are around 76°F, rarely falling below 60°F or exceeding 89°F. The highest daily average high temperature is 80°F on July 18.

Daily low temperatures increase by 6°F, from 49°F to 55°F, rarely falling below 37°F or exceeding 69°F. The highest daily average low temperature is 59°F on July 26.

For reference, on July 18, the hottest day of the year, temperatures in Rapid City typically range from 59°F to 80°F, while on January 29, the coldest day of the year, they range from 14°F to 27°F.

The figure below shows you a compact characterization of the hourly average summer temperatures. 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.

Bjni, Armenia (5,784 miles away) and Sapporo, Japan (5,726 miles) are the far-away foreign places with temperatures most similar to Rapid City (view comparison).

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The summer in Rapid City experiences rapidly decreasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy decreasing from 49% to 35%. The lowest chance of overcast or mostly cloudy conditions is 32% on August 2.

The clearest day of the summer is August 2, with clear, mostly clear, or partly cloudy conditions 68% of the time.

For reference, on January 11, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 77%, while on August 2, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 68%.

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 the summer is essentially constant, remaining around 28% throughout.

For reference, the year's highest daily chance of a wet day is 35% on September 21, and its lowest chance is 15% on February 11.

Rainfall

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

The average sliding 31-day rainfall during the summer in Rapid City is essentially constant, remaining about 2.6 inches throughout, and rarely exceeding 4.6 inches or falling below 1.1 inches.

The lowest average 31-day accumulation is 2.2 inches on July 15.

Over the course of the summer in Rapid City, the length of the day is very rapidly decreasing. From the start to the end of the season, the length of the day decreases by 2 hours, 7 minutes, implying an average daily decrease of 1 minute, 24 seconds, and weekly decrease of 9 minutes, 45 seconds.

The shortest day of the summer is August 31, with 13 hours, 16 minutes of daylight and the longest day is June 20, with 15 hours, 36 minutes of daylight.

The earliest sunrise of the summer in Rapid City is 5:54 AM on June 15 and the latest sunrise is 1 hour, 8 minutes later at 7:02 AM on August 31.

The latest sunset is 9:31 PM on June 25 and the earliest sunset is 1 hour, 13 minutes earlier at 8:18 PM on August 31.

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

For reference, on June 20, the longest day of the year, the Sun rises at 5:54 AM and sets 15 hours, 36 minutes later, at 9:30 PM, while on December 21, the shortest day of the year, it rises at 8:15 AM and sets 8 hours, 47 minutes later, at 5:03 PM.

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.

The figure below presents a compact representation of key lunar data for the summer of 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.

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 increasing during the summer, rising from 3% to 12% over the course of the season.

The highest chance of a muggy day during the summer is 19% on July 29.

For reference, on July 29, the muggiest day of the year, there are muggy conditions 19% of the time, while on November 15, the least muggy day of the year, there are muggy conditions 0% of the time.

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 the summer, remaining within 0.5 miles per hour of 8.8 miles per hour throughout.

For reference, on January 13, the windiest day of the year, the daily average wind speed is 13.2 miles per hour, while on July 22, the calmest day of the year, the daily average wind speed is 8.4 miles per hour.

The lowest daily average wind speed during the summer is 8.4 miles per hour on July 22.

The wind direction in Rapid City during the summer is predominantly out of the south from June 1 to June 12 and from August 25 to August 31 and the west from June 12 to August 25.

Rapid City is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.

The average surface water temperature in Rapid City is very rapidly increasing during the summer, rising by 22°F, from 45°F to 67°F, over the course of the season.

The highest average surface water temperature during the summer is 68°F on August 15.

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 4.6 months (140 days), from around May 17 to around October 4, rarely starting before April 29 or after June 6, and rarely ending before September 18 or after October 23.

The summer in Rapid City is more likely than not fully within the growing season, with the chance that a given day is in the growing season increasing from 84% to 100% over the course of the 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 very rapidly increasing during the summer, increasing by 1,535°F, from 343°F to 1,877°F, over the course of the season.

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 the summer, falling by 1.3 kWh, from 6.6 kWh to 5.3 kWh, over the course of the season.

The highest average daily incident shortwave solar energy during the summer is 7.0 kWh on June 30.

For the purposes of this report, the geographical coordinates of Rapid City are 44.834 deg latitude, -85.283 deg longitude, and 630 ft elevation.

The topography within 2 miles of Rapid City contains only modest variations in elevation, with a maximum elevation change of 335 feet and an average elevation above sea level of 663 feet. Within 10 miles contains only modest variations in elevation (594 feet). Within 50 miles contains significant variations in elevation (1,234 feet).

The area within 2 miles of Rapid City is covered by trees (56%), herbaceous vegetation (13%), and artificial surfaces (12%), within 10 miles by trees (50%) and water (19%), and within 50 miles by trees (51%) and water (26%).