St. Louis Air Quality in June
Across 2019–2025, St. Louis's June air quality had a median AQI of 71 (Moderate) over 210 monitored days in the St. Louis, MO-IL area. 17.6% of June days (37 of 210) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 55.2% of days. The cleanest June on record here was 2019 (median AQI 63, 1 day above 100) and the worst was 2023 (median 101, 15 days above 100, peak AQI 185).
- Good: 8.6%
- Moderate: 73.8%
- Unhealthy for Sensitive Groups: 15.7%
- Unhealthy or worse: 1.9%
Extra Protection for St. Louis Homes
Air quality in St. Louis is moderate (AQI 60), 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
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How is the air in St. Louis in June?
Moderate on a typical day: median AQI 71 across 2019–2025, with 17.6% of June days above AQI 100. Ground-level ozone is the main driver.
- ✓8.6% of June days were Good (AQI 0–50), 73.8% Moderate (51–100).
- ✓37 days of 210 reached AQI 101+; the June peak was 185.
- ✓Best June: 2019; worst June: 2023.
Frequently asked questions
What is the air quality like in St. Louis in June?▾
Across 2019–2025, the median daily AQI in St. Louis in June was 71 (Moderate). 8.6% of days were Good, 73.8% Moderate, and 17.6% reached Unhealthy for Sensitive Groups or worse, based on 210 monitored days in EPA's Air Quality System.
Is June a good time for outdoor exercise in St. Louis?▾
A typical June day in St. Louis is Moderate (median AQI 71): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 6 of June days (17.6%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes St. Louis's June air quality problems?▾
Ground-level ozone set the daily AQI on 55.2% of June days in St. Louis. The highest June AQI recorded in 2019–2025 was 185 (Unhealthy), in 2023.
St. Louis June air quality, year by year
St. Louis June air quality by year (St. Louis, MO-IL, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019cleanest | 30 | 63 | 1 | 143 | O3 |
| 2020 | 30 | 79 | 4 | 122 | O3 |
| 2021 | 30 | 64 | 4 | 119 | PM2.5 |
| 2022 | 30 | 77 | 9 | 147 | O3 |
| 2023worst | 30 | 101 | 15 | 185 | O3 |
| 2024 | 30 | 66 | 2 | 165 | O3 |
| 2025 | 30 | 63 | 2 | 119 | PM2.5 |
What June air means in St. Louis
A typical June day in St. Louis is Moderate (median AQI 71): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 6 of June days (17.6%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
June's median AQI of 71 is above St. Louis's whole-year median of 58, making it one of the area's dirtier periods. Nationally, the median June AQI across every EPA metro area (100,635 metro-days, 2019–2025) is 46, so St. Louis runs above the national June norm; 17.6% of its June days topped AQI 100 versus 3.7% nationally (above average).
June is part of St. Louis's summer season (June, July, August); the summer page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in St. Louis
The latest EPA AirNow observation puts St. Louis's AQI at 60 (PM2.5). The figures above are multi-year month statistics, not today's reading.
View current St. Louis air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (St. Louis, MO-IL), 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.