St. Louis Air Quality in February
Across 2019–2025, St. Louis's February air quality had a median AQI of 57 (Moderate) over 198 monitored days in the St. Louis, MO-IL area. 1.0% of February days (2 of 198) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 91.4% of days. The cleanest February on record here was 2025 (median AQI 52, 0 days above 100) and the worst was 2024 (median 59, 2 days above 100, peak AQI 156).
- Good: 19.7%
- Moderate: 79.3%
- Unhealthy for Sensitive Groups: 0.5%
- Unhealthy or worse: 0.5%
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 February?
Moderate on a typical day: median AQI 57 across 2019–2025, with 1.0% of February days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓19.7% of February days were Good (AQI 0–50), 79.3% Moderate (51–100).
- ✓2 days of 198 reached AQI 101+; the February peak was 156.
- ✓Best February: 2025; worst February: 2024.
Frequently asked questions
What is the air quality like in St. Louis in February?▾
Across 2019–2025, the median daily AQI in St. Louis in February was 57 (Moderate). 19.7% of days were Good, 79.3% Moderate, and 1.0% reached Unhealthy for Sensitive Groups or worse, based on 198 monitored days in EPA's Air Quality System.
Is February a good time for outdoor exercise in St. Louis?▾
A typical February day in St. Louis is Moderate (median AQI 57): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 100 of February days (1.0%) 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 February air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 91.4% of February days in St. Louis. The highest February AQI recorded in 2019–2025 was 156 (Unhealthy), in 2024.
St. Louis February air quality, year by year
St. Louis February air quality by year (St. Louis, MO-IL, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 28 | 60 | 0 | 99 | PM2.5 |
| 2020 | 29 | 55 | 0 | 69 | PM2.5 |
| 2021 | 28 | 56 | 0 | 76 | PM2.5 |
| 2022 | 28 | 58 | 0 | 82 | PM2.5 |
| 2023 | 28 | 58 | 0 | 84 | PM2.5 |
| 2024worst | 29 | 59 | 2 | 156 | PM2.5 |
| 2025cleanest | 28 | 52 | 0 | 71 | PM2.5 |
What February air means in St. Louis
A typical February day in St. Louis is Moderate (median AQI 57): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 100 of February days (1.0%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
February's median AQI of 57 is in line with St. Louis's whole-year median of 58, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median February AQI across every EPA metro area (87,428 metro-days, 2019–2025) is 41, so St. Louis runs above the national February norm; 1.0% of its February days topped AQI 100 versus 0.4% nationally (about the same).
February is part of St. Louis's winter season (December, January, February); the winter 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.