Cincinnati Air Quality in September
Across 2019–2025, Cincinnati's September air quality had a median AQI of 56 (Moderate) over 210 monitored days in the Cincinnati, OH-KY-IN area. 4.8% of September days (10 of 210) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 66.2% of days. The cleanest September on record here was 2022 (median AQI 53, 0 days above 100) and the worst was 2025 (median 68, 7 days above 100, peak AQI 150).
- Good: 23.8%
- Moderate: 71.4%
- Unhealthy for Sensitive Groups: 4.8%
- Unhealthy or worse: 0.0%
Extra Protection for Cincinnati Homes
Air quality in Cincinnati is moderate (AQI 65), with fine particles (PM2.5) the main concern. A True-HEPA purifier gives sensitive groups — kids, seniors and anyone with asthma or allergies — cleaner air indoors on days like today.
Recommended: Coway AP-1512HH Mighty — True HEPA + carbon · CADR ~246 CFM · rooms up to 361 sq ft
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How is the air in Cincinnati in September?
Moderate on a typical day: median AQI 56 across 2019–2025, with 4.8% of September days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓23.8% of September days were Good (AQI 0–50), 71.4% Moderate (51–100).
- ✓10 days of 210 reached AQI 101+; the September peak was 150.
- ✓Best September: 2022; worst September: 2025.
Frequently asked questions
What is the air quality like in Cincinnati in September?▾
Across 2019–2025, the median daily AQI in Cincinnati in September was 56 (Moderate). 23.8% of days were Good, 71.4% Moderate, and 4.8% 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 Cincinnati?▾
A typical September day in Cincinnati is Moderate (median AQI 56): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 21 of September days (4.8%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Cincinnati's September air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 66.2% of September days in Cincinnati. The highest September AQI recorded in 2019–2025 was 150 (Unhealthy for Sensitive Groups), in 2025.
Cincinnati September air quality, year by year
Cincinnati September air quality by year (Cincinnati, OH-KY-IN, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 30 | 61 | 2 | 112 | PM2.5 |
| 2020 | 30 | 55 | 0 | 74 | PM2.5 |
| 2021 | 30 | 57 | 0 | 77 | PM2.5 |
| 2022cleanest | 30 | 53 | 0 | 80 | PM2.5 |
| 2023 | 30 | 54 | 0 | 74 | PM2.5 |
| 2024 | 30 | 52 | 1 | 105 | PM2.5 |
| 2025worst | 30 | 68 | 7 | 150 | O3 |
What September air means in Cincinnati
A typical September day in Cincinnati is Moderate (median AQI 56): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 21 of September days (4.8%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
September's median AQI of 56 is in line with Cincinnati's whole-year median of 56, 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 Cincinnati runs above the national September norm; 4.8% of its September days topped AQI 100 versus 2.7% nationally (above average).
September is part of Cincinnati's fall season (September, October, November); the fall page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Cincinnati
The latest EPA AirNow observation puts Cincinnati's AQI at 65 (PM2.5). The figures above are multi-year month statistics, not today's reading.
View current Cincinnati air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Cincinnati, OH-KY-IN), 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.