Today | Weather | Monday, September 21, 2026

Weather in Rapid City, South Dakota

11:55 AM
Now
Rainy Weather
55° F
Feels Like 52°
Precipitation 53 %
Wind 9 mph
UV Index (0 - 11+) 1
Humidity 88 %
Today
Rainy Weather
Day 59°
Night 50°
Precipitation 86 %
Wind 9 mph
UV Index (0 - 11+) 2

Rapid City Weather Forecast Updated

22 minutes ago
Last updated on
Weather Forecast History
Last Year's Weather on This Day (September 21, 2025)
Sunny Weather

Day

82°

Night

54°

Wind

7 mph

UV Index

50

Precipitation

1 %

Air Quality in Rapid City

NOW
23 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 0.9 µg/m³
PM10 1.83 µg/m³
O3 0.025 ppm
NO2 0.3 ppb
SO2 0 ppb
CO 0.12 ppm
NH3 0.38 µg/m³
NO 0.12 µg/m³
PM2.5 – Fine particles <2.5μm
PM10 – Inhalable particles <10μm
O3 – Ozone
NO2 – Nitrogen dioxide
SO2 – Sulfur dioxide
CO – Carbon monoxide
NH3 – Ammonia
NO – Nitric oxide

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

Show raw pollutant concentrations (µg/m³)
PM2.50.9 µg/m³
PM101.83 µg/m³
O348.52 µg/m³
NO20.63 µg/m³
SO20.11 µg/m³
CO136.4 µg/m³
NH30.38 µg/m³
NO0.12 µg/m³