Louisville Air Quality in October
Across 2019–2025, Louisville's October air quality had a median AQI of 52 (Moderate) over 217 monitored days in the Louisville/Jefferson County, KY-IN area. 0.0% of October days (0 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 80.6% of days. The cleanest October on record here was 2025 (median AQI 42, 0 days above 100) and the worst was 2024 (median 56, 0 days above 100, peak AQI 80).
- Good: 44.7%
- Moderate: 55.3%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
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How is the air in Louisville in October?
Moderate on a typical day: median AQI 52 across 2019–2025, with 0.0% of October days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓44.7% of October days were Good (AQI 0–50), 55.3% Moderate (51–100).
- ✓0 days of 217 reached AQI 101+; the October peak was 90.
- ✓Best October: 2025; worst October: 2024.
Frequently asked questions
What is the air quality like in Louisville in October?▾
Across 2019–2025, the median daily AQI in Louisville in October was 52 (Moderate). 44.7% of days were Good, 55.3% Moderate, and 0.0% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is October a good time for outdoor exercise in Louisville?▾
A typical October day in Louisville is Moderate (median AQI 52): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and fewer than 1% of October days 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 October air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 80.6% of October days in Louisville. The highest October AQI recorded in 2019–2025 was 90 (Moderate), in 2024.
Louisville October air quality, year by year
Louisville October 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 |
|---|---|---|---|---|---|
| 2019 | 31 | 51 | 0 | 67 | PM2.5 |
| 2020 | 31 | 51 | 0 | 66 | PM2.5 |
| 2021 | 31 | 51 | 0 | 63 | PM2.5 |
| 2022 | 31 | 53 | 0 | 71 | PM2.5 |
| 2023 | 31 | 50 | 0 | 67 | PM2.5 |
| 2024worst | 31 | 56 | 0 | 80 | PM2.5 |
| 2025cleanest | 31 | 42 | 0 | 90 | PM2.5 |
What October air means in Louisville
A typical October day in Louisville is Moderate (median AQI 52): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and fewer than 1% of October days reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
October's median AQI of 52 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 October AQI across every EPA metro area (102,872 metro-days, 2019–2025) is 38, so Louisville runs above the national October norm; 0.0% of its October days topped AQI 100 versus 1.3% nationally (below average).
October is part of Louisville's fall season (September, October, November); the fall page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Louisville
The latest EPA AirNow observation puts Louisville's AQI at 38 (PM2.5). The figures above are multi-year month 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.