Rapid City Climate by Month
Rapid City, South Dakota, United States
Hot summers and cold winters, with most rain from April to August.
Rapid City has hot summers and cold winters, with most rain from April to August. July is the warmest month, with highs around 87°F (30°C); January is the coolest at 39°F (4°C), and nights dip to 14°F (-10°C). Of the 17 in (441 mm) of rain in a typical year, 73% falls from April to August. December and January are almost completely dry.
- Warmest month
- 87°F(30°C)
- Average high, July
- Coldest nights
- 14°F(-10°C)
- Average low, January
- Rain per year
- 17 in(441 mm)
- Wettest: May
- Humidity
- 55%
- Sunniest: July
Best and worst months in Rapid City
Best for weatherThe most comfortable weather comes in September, with highs around 77°F (25°C) and about 1.1 in (29 mm) of rain a month.
Least pleasantJanuary and February are the least pleasant; January is the coldest, with highs of only 39°F (4°C).
Comfort combines how close the afternoon high is to 75°F (24°C) with how much rain falls and how humid it is. See where the weather is best in September.
Temperature and rain through the year
Highs and lows (°F)
Average highAverage low
Rain (in per month)
Rapid City weather by month
| Month | High | Low | Rain | Humidity | Sun |
|---|---|---|---|---|---|
| JanJanuary | 39°F(4°C) | 14°F(-10°C) | 0.3 in(7 mm) | 61% | 1.9 |
| FebFebruary | 40°F(5°C) | 15°F(-9°C) | 0.4 in(10 mm) | 59% | 2.7 |
| MarMarch | 50°F(10°C) | 24°F(-5°C) | 0.8 in(21 mm) | 55% | 4.0 |
| AprApril | 58°F(14°C) | 32°F(0°C) | 2.0 in(50 mm) | 59% | 4.8 |
| MayMay | 67°F(20°C) | 43°F(6°C) | 3.4 in(86 mm) | 61% | 5.9 |
| JunJune | 78°F(26°C) | 52°F(11°C) | 3.1 in(80 mm) | 56% | 6.3 |
| JulJuly | 87°F(30°C) | 59°F(15°C) | 2.2 in(55 mm) | 51% | 6.8 |
| AugAugust | 85°F(30°C) | 57°F(14°C) | 1.9 in(49 mm) | 50% | 5.9 |
| SepSeptemberBest | 77°F(25°C) | 47°F(8°C) | 1.1 in(29 mm) | 47% | 4.6 |
| OctOctober | 62°F(17°C) | 34°F(1°C) | 1.4 in(36 mm) | 52% | 3.0 |
| NovNovember | 49°F(9°C) | 23°F(-5°C) | 0.4 in(10 mm) | 56% | 1.9 |
| DecDecember | 41°F(5°C) | 16°F(-9°C) | 0.3 in(8 mm) | 57% | 1.6 |
1991–2020 averages. Sun is solar radiation in kWh/m² per day. Highlighted: the most comfortable months.
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