May Weather in Rapid City, United States

Last updated: June 24, 2025

In May, the average temperature in Rapid City, United States hovers around 13°C (56°F), offering a mild climate for visitors. However, be prepared for temperature fluctuations, as it can dip as low as -3°C (27°F) or soar up to 33°C (92°F). With an average precipitation of 119 mm (4.7 in) spread across 12 days, and an average humidity level of 82%, it's wise to pack accordingly for a comfortable experience!

May Temperature in Rapid City

In May in Rapid City, the average temperature is 13°C (56°F). Maximum temperatures can reach 33°C (92°F), while minimums can dip to as low as -3°C (27°F). Be prepared for a wide range of temperatures when traveling during this month.

May Weather in Rapid City: Daily Temperature Highs, Lows, and Averages

The chart illustrates May temperature patterns in Rapid City, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Rapid City, May typically has an average temperature of 13°C (56°F), with highs reaching up to 33°C (92°F) and lows dropping to around -3°C (27°F).
JanFebMarAprMayJunJulAugSepOctNovDec222231415565706861493528
Data source: Temperature data for Rapid City generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

May Precipitation in Rapid City

In Rapid City in May, the total precipitation amount is 119 mm (4.7 in), falling over a span of 12 days.

May Precipitation Trends in Rapid City

The chart displays monthly precipitation patterns in Rapid City, with values for each month alongside May’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how May’s conditions compare to those of other months. In Rapid City, May typically receives around 119 mm (4.7 inches) of precipitation spread over approximately 12 days.
JanFebMarAprMayJunJulAugSepOctNovDec5762629711911110391781317774
Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.
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May Humidity in Rapid City

In Rapid City in May, humidity is 82%. With an average temperature of 13°C (56°F), this humidity feels like a damp blanket wrapping around you, making it feel much cooler than it is and creating a heavy atmosphere that can be exhausting for travelers.

May Average Humidity in Rapid City

This chart illustrates the average monthly humidity levels in Rapid City, with May’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In May, average humidity in Rapid City is approximately 82%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec91%91%87%87%82%79%76%76%79%83%86%87%
Data source: Humidity data for May generated using information from the Copernicus Climate Change Service.

May UV Index in Rapid City

In Rapid City in May, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Rapid City.

Maximum UV Index Levels in Rapid City for May

The chart shows the monthly maximum UV Index (UVI) for Rapid City in May, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In May, the maximum UV index in Rapid City typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec2457910987532
Data source: Rapid City May UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How May Weather in Rapid City Compares to Other Months

Weather in Rapid City varies notably across the year, with each month offering distinct climate conditions. This page compares May’s weather to other months in Rapid City, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Rapid City, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-6°C (22°F)57 mm (2.2 inches)91%low
February Weather-6°C (22°F)62 mm (2.4 inches)91%moderate
March Weather-1°C (31°F)62 mm (2.4 inches)87%moderate
April Weather5°C (42°F)97 mm (3.8 inches)87%high
May Weather13°C (56°F)119 mm (4.7 inches)82%very high
June Weather19°C (66°F)111 mm (4.4 inches)79%very high
July Weather21°C (71°F)103 mm (4.1 inches)75%very high
August Weather20°C (68°F)91 mm (3.6 inches)76%very high
September Weather16°C (61°F)78 mm (3.1 inches)79%high
October Weather10°C (49°F)131 mm (5.2 inches)83%moderate
November Weather2°C (35°F)77 mm (3.0 inches)86%moderate
December Weather-2°C (28°F)74 mm (2.9 inches)87%low

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