Sioux Falls Air Quality in September
Across 2019–2025, Sioux Falls's September air quality had a median AQI of 41 (Good) over 209 monitored days in the Sioux Falls, SD area. 0.5% of September days (1 of 209) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 66.0% of days. The cleanest September on record here was 2019 (median AQI 31, 0 days above 100) and the worst was 2023 (median 51, 1 day above 100, peak AQI 142).
- Good: 73.2%
- Moderate: 26.3%
- Unhealthy for Sensitive Groups: 0.5%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Sioux Falls
Today's main pollutant in Sioux Falls is ground-level ozone (AQI 24). Important: standard HEPA filters do NOT remove ozone — only a purifier with a substantial activated-carbon bed adsorbs it. The biggest wins are cutting indoor sources (gas appliances, certain "ionizer" purifiers) and ventilating when outdoor ozone is low (early morning). A high-carbon unit helps with the gases and VOCs that linger indoors.
Recommended: Levoit Core 300 — True HEPA + activated carbon · CADR ~141 CFM · rooms up to 219 sq ft
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How is the air in Sioux Falls in September?
Good on a typical day: median AQI 41 across 2019–2025, with 0.5% of September days above AQI 100. Ground-level ozone is the main driver.
- ✓73.2% of September days were Good (AQI 0–50), 26.3% Moderate (51–100).
- ✓1 day of 209 reached AQI 101+; the September peak was 142.
- ✓Best September: 2019; worst September: 2023.
Frequently asked questions
What is the air quality like in Sioux Falls in September?▾
Across 2019–2025, the median daily AQI in Sioux Falls in September was 41 (Good). 73.2% of days were Good, 26.3% Moderate, and 0.5% reached Unhealthy for Sensitive Groups or worse, based on 209 monitored days in EPA's Air Quality System.
Is September a good time for outdoor exercise in Sioux Falls?▾
A typical September day in Sioux Falls sits in the Good range (median AQI 41), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of September days reached AQI 101+ in 2019–2025.
Which pollutant causes Sioux Falls's September air quality problems?▾
Ground-level ozone set the daily AQI on 66.0% of September days in Sioux Falls. The highest September AQI recorded in 2019–2025 was 142 (Unhealthy for Sensitive Groups), in 2023.
Sioux Falls September air quality, year by year
Sioux Falls September air quality by year (Sioux Falls, SD, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019cleanest | 30 | 31 | 0 | 58 | O3 |
| 2020 | 30 | 40 | 0 | 67 | O3 |
| 2021 | 30 | 41 | 0 | 59 | O3 |
| 2022 | 30 | 40 | 0 | 84 | O3 |
| 2023worst | 30 | 51 | 1 | 142 | O3 |
| 2024 | 29 | 45 | 0 | 80 | O3 |
| 2025 | 30 | 42 | 0 | 74 | PM2.5 |
What September air means in Sioux Falls
A typical September day in Sioux Falls sits in the Good range (median AQI 41), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of September days reached AQI 101+ in 2019–2025.
September's median AQI of 41 is in line with Sioux Falls's whole-year median of 38, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median September AQI across every EPA metro area (100,699 metro-days, 2019–2025) is 43, so Sioux Falls runs in line with the national September norm; 0.5% of its September days topped AQI 100 versus 2.7% nationally (below average).
September is part of Sioux Falls's fall season (September, October, November); the fall page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Sioux Falls
The latest EPA AirNow observation puts Sioux Falls's AQI at 24 (O3). The figures above are multi-year month statistics, not today's reading.
View current Sioux Falls air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Sioux Falls, SD), 2019–2025. Daily AQI per CBSA is the highest AQI reported by any monitor in the area that day; the defining parameter is the pollutant that set it. Month and season statistics pool every such day in the period across all years listed. Retrieved 2026-09-09.