Louisville Air Quality in January
Across 2019–2025, Louisville's January air quality had a median AQI of 54 (Moderate) over 217 monitored days in the Louisville/Jefferson County, KY-IN area. 0.0% of January days (0 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 92.6% of days. The cleanest January on record here was 2024 (median AQI 44, 0 days above 100) and the worst was 2019 (median 57, 0 days above 100, peak AQI 71).
- Good: 37.8%
- Moderate: 62.2%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
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How is the air in Louisville in January?
Moderate on a typical day: median AQI 54 across 2019–2025, with 0.0% of January days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓37.8% of January days were Good (AQI 0–50), 62.2% Moderate (51–100).
- ✓0 days of 217 reached AQI 101+; the January peak was 91.
- ✓Best January: 2024; worst January: 2019.
Frequently asked questions
What is the air quality like in Louisville in January?▾
Across 2019–2025, the median daily AQI in Louisville in January was 54 (Moderate). 37.8% of days were Good, 62.2% Moderate, and 0.0% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is January a good time for outdoor exercise in Louisville?▾
A typical January day in Louisville is Moderate (median AQI 54): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and fewer than 1% of January 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 January air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 92.6% of January days in Louisville. The highest January AQI recorded in 2019–2025 was 91 (Moderate), in 2019.
Louisville January air quality, year by year
Louisville January 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 |
|---|---|---|---|---|---|
| 2019worst | 31 | 57 | 0 | 71 | PM2.5 |
| 2020 | 31 | 53 | 0 | 71 | PM2.5 |
| 2021 | 31 | 54 | 0 | 80 | PM2.5 |
| 2022 | 31 | 56 | 0 | 91 | PM2.5 |
| 2023 | 31 | 56 | 0 | 72 | PM2.5 |
| 2024cleanest | 31 | 44 | 0 | 64 | PM2.5 |
| 2025 | 31 | 52 | 0 | 82 | PM2.5 |
What January air means in Louisville
A typical January day in Louisville is Moderate (median AQI 54): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and fewer than 1% of January days reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
January's median AQI of 54 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 January AQI across every EPA metro area (95,602 metro-days, 2019–2025) is 39, so Louisville runs above the national January norm; 0.0% of its January days topped AQI 100 versus 0.7% nationally (about the same).
January is part of Louisville's winter season (December, January, February); the winter 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.