Des Moines Air Quality in September
Across 2019–2025, Des Moines's September air quality had a median AQI of 43 (Good) over 210 monitored days in the Des Moines-West Des Moines, IA area. 0.5% of September days (1 of 210) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 56.7% of days. The cleanest September on record here was 2020 (median AQI 34, 0 days above 100) and the worst was 2023 (median 54, 1 day above 100, peak AQI 105).
- Good: 68.1%
- Moderate: 31.4%
- Unhealthy for Sensitive Groups: 0.5%
- Unhealthy or worse: 0.0%
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How is the air in Des Moines in September?
Good on a typical day: median AQI 43 across 2019–2025, with 0.5% of September days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓68.1% of September days were Good (AQI 0–50), 31.4% Moderate (51–100).
- ✓1 day of 210 reached AQI 101+; the September peak was 105.
- ✓Best September: 2020; worst September: 2023.
Frequently asked questions
What is the air quality like in Des Moines in September?▾
Across 2019–2025, the median daily AQI in Des Moines in September was 43 (Good). 68.1% of days were Good, 31.4% Moderate, and 0.5% reached Unhealthy for Sensitive Groups or worse, based on 210 monitored days in EPA's Air Quality System.
Is September a good time for outdoor exercise in Des Moines?▾
A typical September day in Des Moines sits in the Good range (median AQI 43), 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 Des Moines's September air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 56.7% of September days in Des Moines. The highest September AQI recorded in 2019–2025 was 105 (Unhealthy for Sensitive Groups), in 2023.
Des Moines September air quality, year by year
Des Moines September air quality by year (Des Moines-West Des Moines, IA, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 30 | 38 | 0 | 63 | PM2.5 |
| 2020cleanest | 30 | 34 | 0 | 56 | O3 |
| 2021 | 30 | 44 | 0 | 74 | O3 |
| 2022 | 30 | 38 | 0 | 55 | O3 |
| 2023worst | 30 | 54 | 1 | 105 | PM2.5 |
| 2024 | 30 | 44 | 0 | 93 | O3 |
| 2025 | 30 | 49 | 0 | 76 | PM2.5 |
What September air means in Des Moines
A typical September day in Des Moines sits in the Good range (median AQI 43), 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 43 is in line with Des Moines's whole-year median of 44, 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 Des Moines 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 Des Moines's fall season (September, October, November); the fall page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Des Moines
The latest EPA AirNow observation puts Des Moines's AQI at 32 (PM2.5). The figures above are multi-year month statistics, not today's reading.
View current Des Moines air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Des Moines-West Des Moines, IA), 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.