Louisville Air Quality in Summer
Across 2019–2025, Louisville's summer (June–August) air quality had a median AQI of 56 (Moderate) over 644 monitored days in the Louisville/Jefferson County, KY-IN area. 8.9% of summer days (57 of 644) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 51.6% of days. The cleanest summer on record here was 2019 (median AQI 55, 4 days above 100) and the worst was 2023 (median 65, 20 days above 100, peak AQI 182).
- Good: 30.7%
- Moderate: 60.4%
- Unhealthy for Sensitive Groups: 8.4%
- Unhealthy or worse: 0.5%
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How is the air in Louisville in summer?
Moderate on a typical day: median AQI 56 across 2019–2025, with 8.9% of summer days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓30.7% of summer days were Good (AQI 0–50), 60.4% Moderate (51–100).
- ✓57 days of 644 reached AQI 101+; the summer peak was 182.
- ✓Cleanest month: August; worst month: June.
Frequently asked questions
What is the air quality like in Louisville in summer?▾
Across 2019–2025, the median daily AQI in Louisville in summer was 56 (Moderate). 30.7% of days were Good, 60.4% Moderate, and 8.9% reached Unhealthy for Sensitive Groups or worse, based on 644 monitored days in EPA's Air Quality System.
Is summer a good time for outdoor exercise in Louisville?▾
A typical summer day in Louisville 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 11 of summer days (8.9%) 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 summer air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 51.6% of summer days in Louisville. The highest summer AQI recorded in 2019–2025 was 182 (Unhealthy), in 2023.
Louisville summer air quality, year by year
Louisville summer 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 | 92 | 55 | 4 | 136 | PM2.5 |
| 2020 | 92 | 54 | 6 | 143 | O3 |
| 2021 | 92 | 55 | 5 | 143 | PM2.5 |
| 2022 | 92 | 55 | 6 | 136 | PM2.5 |
| 2023worst | 92 | 65 | 20 | 182 | PM2.5 |
| 2024 | 92 | 58 | 12 | 156 | O3 |
| 2025 | 92 | 56 | 4 | 153 | O3 |
What summer air means in Louisville
A typical summer day in Louisville 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 11 of summer days (8.9%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Summer's median AQI of 56 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 Summer AQI across every EPA metro area (308,645 metro-days, 2019–2025) is 46, so Louisville runs above the national Summer norm; 8.9% of its Summer days topped AQI 100 versus 3.6% nationally (above average).
Within the season, August is the cleanest month (median AQI 54, 5.5% of days above 100) and June the worst (median 58, 12.0% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Louisville
The latest EPA AirNow observation puts Louisville's AQI at 32 (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.