Rochester Air Quality in September
Across 2019–2025, Rochester's September air quality had a median AQI of 35 (Good) over 210 monitored days in the Rochester, NY area. 0.0% of September days (0 of 210) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 53.8% of days. The cleanest September on record here was 2022 (median AQI 29, 0 days above 100) and the worst was 2023 (median 42, 0 days above 100, peak AQI 62).
- Good: 81.4%
- Moderate: 18.6%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
Reducing Indoor Ozone
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, "ionizer" purifiers) and ventilating when outdoor ozone is low (early morning). A high-carbon unit also helps with the gases and VOCs that linger indoors.
Recommended: Coway AP-1512HH (HEPA + Carbon) — True HEPA + activated carbon layer · rooms up to 361 sq ft
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How is the air in Rochester in September?
Good on a typical day: median AQI 35 across 2019–2025, with 0.0% of September days above AQI 100. Ground-level ozone is the main driver.
- ✓81.4% of September days were Good (AQI 0–50), 18.6% Moderate (51–100).
- ✓0 days of 210 reached AQI 101+; the September peak was 67.
- ✓Best September: 2022; worst September: 2023.
Frequently asked questions
What is the air quality like in Rochester in September?▾
Across 2019–2025, the median daily AQI in Rochester in September was 35 (Good). 81.4% of days were Good, 18.6% Moderate, and 0.0% 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 Rochester?▾
A typical September day in Rochester sits in the Good range (median AQI 35), 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 Rochester's September air quality problems?▾
Ground-level ozone set the daily AQI on 53.8% of September days in Rochester. The highest September AQI recorded in 2019–2025 was 67 (Moderate), in 2023.
Rochester September air quality, year by year
Rochester September air quality by year (Rochester, NY, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 30 | 34 | 0 | 59 | O3 |
| 2020 | 30 | 32 | 0 | 67 | O3 |
| 2021 | 30 | 35 | 0 | 57 | O3 |
| 2022cleanest | 30 | 29 | 0 | 58 | PM2.5 |
| 2023worst | 30 | 42 | 0 | 62 | PM2.5 |
| 2024 | 30 | 39 | 0 | 61 | O3 |
| 2025 | 30 | 40 | 0 | 54 | O3 |
What September air means in Rochester
A typical September day in Rochester sits in the Good range (median AQI 35), 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 35 is below Rochester's whole-year median of 42, making it one of the area's cleaner periods. Nationally, the median September AQI across every EPA metro area (100,699 metro-days, 2019–2025) is 43, so Rochester runs below the national September norm; 0.0% of its September days topped AQI 100 versus 2.7% nationally (below average).
September is part of Rochester's fall season (September, October, November); the fall page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Rochester, NY), 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.