Indianapolis Air Quality in Fall
Across 2019–2025, Indianapolis's fall (September–November) air quality had a median AQI of 57 (Moderate) over 637 monitored days in the Indianapolis-Carmel-Anderson, IN area. 3.7% of fall days (23 of 637) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 87.4% of days. The cleanest fall on record here was 2020 (median AQI 54, 2 days above 100) and the worst was 2022 (median 59, 5 days above 100, peak AQI 154).
- Good: 29.0%
- Moderate: 67.3%
- Unhealthy for Sensitive Groups: 3.5%
- Unhealthy or worse: 0.2%
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How is the air in Indianapolis in fall?
Moderate on a typical day: median AQI 57 across 2019–2025, with 3.7% of fall days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓29.0% of fall days were Good (AQI 0–50), 67.3% Moderate (51–100).
- ✓23 days of 637 reached AQI 101+; the fall peak was 154.
- ✓Cleanest month: October; worst month: November.
Frequently asked questions
What is the air quality like in Indianapolis in fall?▾
Across 2019–2025, the median daily AQI in Indianapolis in fall was 57 (Moderate). 29.0% of days were Good, 67.3% Moderate, and 3.7% reached Unhealthy for Sensitive Groups or worse, based on 637 monitored days in EPA's Air Quality System.
Is fall a good time for outdoor exercise in Indianapolis?▾
A typical fall day in Indianapolis is Moderate (median AQI 57): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 27 of fall days (3.7%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Indianapolis's fall air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 87.4% of fall days in Indianapolis. The highest fall AQI recorded in 2019–2025 was 154 (Unhealthy), in 2022.
Indianapolis fall air quality, year by year
Indianapolis fall air quality by year (Indianapolis-Carmel-Anderson, IN, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 91 | 58 | 2 | 119 | PM2.5 |
| 2020cleanest | 91 | 54 | 2 | 144 | PM2.5 |
| 2021 | 91 | 56 | 4 | 111 | PM2.5 |
| 2022worst | 91 | 59 | 5 | 154 | PM2.5 |
| 2023 | 91 | 56 | 3 | 138 | PM2.5 |
| 2024 | 91 | 58 | 2 | 138 | PM2.5 |
| 2025 | 91 | 55 | 5 | 122 | PM2.5 |
What fall air means in Indianapolis
A typical fall day in Indianapolis is Moderate (median AQI 57): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 27 of fall days (3.7%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Fall's median AQI of 57 is in line with Indianapolis's whole-year median of 56, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median Fall AQI across every EPA metro area (296,275 metro-days, 2019–2025) is 40, so Indianapolis runs above the national Fall norm; 3.7% of its Fall days topped AQI 100 versus 1.5% nationally (above average).
Within the season, October is the cleanest month (median AQI 55, 1.4% of days above 100) and November the worst (median 58, 6.7% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Indianapolis
The latest EPA AirNow observation puts Indianapolis's AQI at 47 (PM2.5). The figures above are multi-year season statistics, not today's reading.
View current Indianapolis air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Indianapolis-Carmel-Anderson, 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.