Dayton Air Quality in September
Across 2019–2025, Dayton's September air quality had a median AQI of 49 (Good) over 210 monitored days in the Dayton, OH area. 1.0% of September days (2 of 210) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 55.7% of days. The cleanest September on record here was 2022 (median AQI 40, 0 days above 100) and the worst was 2025 (median 57, 2 days above 100, peak AQI 126).
- Good: 55.7%
- Moderate: 43.3%
- Unhealthy for Sensitive Groups: 1.0%
- Unhealthy or worse: 0.0%
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How is the air in Dayton in September?
Good on a typical day: median AQI 49 across 2019–2025, with 1.0% of September days above AQI 100. Ground-level ozone is the main driver.
- ✓55.7% of September days were Good (AQI 0–50), 43.3% Moderate (51–100).
- ✓2 days of 210 reached AQI 101+; the September peak was 126.
- ✓Best September: 2022; worst September: 2025.
Frequently asked questions
What is the air quality like in Dayton in September?▾
Across 2019–2025, the median daily AQI in Dayton in September was 49 (Good). 55.7% of days were Good, 43.3% Moderate, and 1.0% 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 Dayton?▾
A typical September day in Dayton sits in the Good range (median AQI 49), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 100 of September days (1.0%) reached AQI 101+ in 2019–2025.
Which pollutant causes Dayton's September air quality problems?▾
Ground-level ozone set the daily AQI on 55.7% of September days in Dayton. The highest September AQI recorded in 2019–2025 was 126 (Unhealthy for Sensitive Groups), in 2025.
Dayton September air quality, year by year
Dayton September air quality by year (Dayton, OH, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 30 | 54 | 0 | 87 | O3 |
| 2020 | 30 | 49 | 0 | 65 | PM2.5 |
| 2021 | 30 | 48 | 0 | 80 | O3 |
| 2022cleanest | 30 | 40 | 0 | 67 | O3 |
| 2023 | 30 | 46 | 0 | 61 | O3 |
| 2024 | 30 | 45 | 0 | 90 | O3 |
| 2025worst | 30 | 57 | 2 | 126 | O3 |
What September air means in Dayton
A typical September day in Dayton sits in the Good range (median AQI 49), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 100 of September days (1.0%) reached AQI 101+ in 2019–2025.
September's median AQI of 49 is in line with Dayton's whole-year median of 51, 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 Dayton runs above the national September norm; 1.0% of its September days topped AQI 100 versus 2.7% nationally (below average).
September is part of Dayton's fall season (September, October, November); the fall page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Dayton
The latest EPA AirNow observation puts Dayton's AQI at 50 (PM2.5). The figures above are multi-year month statistics, not today's reading.
View current Dayton air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Dayton, OH), 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.