Louisville Air Quality in Fall
Across 2019–2025, Louisville's fall (September–November) air quality had a median AQI of 53 (Moderate) over 637 monitored days in the Louisville/Jefferson County, KY-IN area. 1.7% of fall days (11 of 637) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 77.6% of days. The cleanest fall on record here was 2019 (median AQI 54, 0 days above 100) and the worst was 2025 (median 52, 6 days above 100, peak AQI 140).
- Good: 40.2%
- Moderate: 58.1%
- Unhealthy for Sensitive Groups: 1.7%
- Unhealthy or worse: 0.0%
Extra Protection for Louisville Homes
Air quality in Louisville is moderate (AQI 61), 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
As an Amazon Associate, we earn from qualifying purchases.
How is the air in Louisville in fall?
Moderate on a typical day: median AQI 53 across 2019–2025, with 1.7% of fall days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓40.2% of fall days were Good (AQI 0–50), 58.1% Moderate (51–100).
- ✓11 days of 637 reached AQI 101+; the fall peak was 140.
- ✓Cleanest month: October; worst month: September.
Frequently asked questions
What is the air quality like in Louisville in fall?▾
Across 2019–2025, the median daily AQI in Louisville in fall was 53 (Moderate). 40.2% of days were Good, 58.1% Moderate, and 1.7% 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 Louisville?▾
A typical fall day in Louisville is Moderate (median AQI 53): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 59 of fall days (1.7%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Louisville's fall air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 77.6% of fall days in Louisville. The highest fall AQI recorded in 2019–2025 was 140 (Unhealthy for Sensitive Groups), in 2025.
Louisville fall air quality, year by year
Louisville fall air quality by year (Louisville/Jefferson County, KY-IN, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019cleanest | 91 | 54 | 0 | 97 | PM2.5 |
| 2020 | 91 | 52 | 1 | 108 | PM2.5 |
| 2021 | 91 | 51 | 1 | 112 | PM2.5 |
| 2022 | 91 | 53 | 2 | 120 | PM2.5 |
| 2023 | 91 | 54 | 0 | 96 | PM2.5 |
| 2024 | 91 | 51 | 1 | 108 | PM2.5 |
| 2025worst | 91 | 52 | 6 | 140 | PM2.5 |
What fall air means in Louisville
A typical fall day in Louisville is Moderate (median AQI 53): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 59 of fall days (1.7%) 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 53 is in line with Louisville's whole-year median of 54, 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 Louisville runs above the national Fall norm; 1.7% of its Fall days topped AQI 100 versus 1.5% nationally (about the same).
Within the season, October is the cleanest month (median AQI 52, 0.0% of days above 100) and September the worst (median 53, 4.3% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Louisville
The latest EPA AirNow observation puts Louisville's AQI at 61 (PM2.5). The figures above are multi-year season statistics, not today's reading.
View current Louisville air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Louisville/Jefferson County, 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.