Rapid City, SD Weather
Rapid City hourly forecast: next 24 hours
Today's high of 71°F (22°C) is about 5°F (3°C) below the typical September high of 76°F (25°C).
Current conditions in detail
Rapid City weather tomorrow (Wednesday, September 16)
Tomorrow in Rapid City looks overcast, with a high of 86° and an overnight low of 55°. Precipitation chance is modest at 38%. Winds top out near 19 mph, and the UV index reaches 6 (moderate).
Rapid City 14-day forecast
About the weather in Rapid City
Seasons are the whole story in Rapid City. The gap between an average July and an average February is 27°C - big day-to-night temperature swings and modest rainfall - which in practice means 86°F (30°C) afternoons at one end of the calendar and 37°F (3°C) at the other.
Rapid City weather: quick facts
- Hottest month: July - highs near 86°F (30°C)
- Coldest month: February - highs near 37°F (3°C)
- Decade extremes (2015-2024): 105°F (41°C) high · -21°F (-30°C) low
- Wettest month: May (12 rainy days) · Sunniest: July (13.5 h sun/day)
- Climate type: semi-arid
- Annual swing: 27°C between the average warmest and coolest month · day to night: 11°C
- Snow: about 22 days a year
- Months averaging 30°C or hotter: 1
- Average humidity: 57%
Temperatures through the year
July is the warm end of the year, averaging 86°F (30°C) by day and 63°F (17°C) overnight. February is the coolest month, with highs of 37°F (3°C) and lows near 17°F (-8°C). Sunshine averages 9.9 hours a day over the year, peaking in July at 13.5 hours.
Rain, sun and snow
Between the average July and the average February lie 27°C, a wider spread than 91% of the 3496 cities in our dataset. Relative humidity averages 57% across the year, drier than about 89% of the cities we track. Days and nights are about 11°C apart on average - wider than roughly 86% of the cities we track. Precipitation concentrates in May - 3.4 inches (87 mm) on 12 days - and thins out by January. Across the gridded 2015-2024 daily record, the highest daily maximum for this location was 105°F (41°C) and the lowest daily minimum -21°F (-30°C).
Season by season
Spring (March through May)
Spring in Rapid City is mild, with daytime highs averaging 56°F (13°C) and nights around 35°F (2°C); expect showers on roughly 27 days across the season, plus about 8 snowy days. Daylight is generous - around 10.1 hours of sun a day.
Summer (June through August)
Summer sits firmly in the heat here - highs near 83°F (28°C), nights near 61°F (16°C), and expect showers on roughly 24 days across the season. Daylight is generous - around 13.1 hours of sun a day.
Fall (September through November)
Fall is crisp but comfortable here - highs near 61°F (16°C), nights near 41°F (5°C), and rain comes on about 15 days over the three months, plus about 4 snowy days.
Winter (December through February)
Winter in Rapid City runs to hard cold, with daytime highs averaging 37°F (3°C) and nights around 18°F (-8°C); rain comes on about 15 days over the three months, plus about 10 snowy days. Wind sharpens cold like this considerably; pair the forecast winds with the wind speed converter to judge exposed conditions.
Average temperatures in Rapid City by month
| Month | High | Low | Rain days | Precipitation | Sunshine | Humidity |
|---|---|---|---|---|---|---|
| January | 37° | 18° | 4 | 0.5 in | 7.2 h/day | 62% |
| February | 37° | 17° | 6 | 0.9 in | 8.2 h/day | 58% |
| March | 47° | 26° | 6 | 1.1 in | 9.3 h/day | 58% |
| April | 55° | 33° | 9 | 2.4 in | 10.2 h/day | 58% |
| May | 65° | 45° | 12 | 3.4 in | 10.9 h/day | 61% |
| June | 80° | 58° | 9 | 2.6 in | 13.1 h/day | 55% |
| July | 86° | 63° | 8 | 1.6 in | 13.5 h/day | 52% |
| August | 83° | 61° | 6 | 1.6 in | 12.6 h/day | 52% |
| September | 76° | 54° | 5 | 1.1 in | 10.6 h/day | 52% |
| October | 60° | 40° | 6 | 1.5 in | 8.9 h/day | 55% |
| November | 48° | 29° | 4 | 0.6 in | 7.7 h/day | 55% |
| December | 37° | 20° | 5 | 0.9 in | 6.8 h/day | 61% |