St. Paul Air Quality in August
Across 2019–2025, St. Paul's August air quality had a median AQI of 52 (Moderate) over 217 monitored days in the Minneapolis-St. Paul-Bloomington, MN-WI area. 1.4% of August days (3 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 65.9% of days. The cleanest August on record here was 2022 (median AQI 46, 0 days above 100) and the worst was 2025 (median 56, 2 days above 100, peak AQI 173).
- Good: 46.1%
- Moderate: 52.5%
- Unhealthy for Sensitive Groups: 0.9%
- Unhealthy or worse: 0.5%
Reduce Indoor Ozone in St. Paul
Today's main pollutant in St. Paul is ground-level ozone (AQI 25). Important: standard HEPA filters do NOT remove ozone — only a purifier with a substantial activated-carbon bed adsorbs it. The biggest wins are cutting indoor sources (gas appliances, certain "ionizer" purifiers) and ventilating when outdoor ozone is low (early morning). A high-carbon unit helps with the gases and VOCs that linger indoors.
Recommended: Levoit Core 300 — True HEPA + activated carbon · CADR ~141 CFM · rooms up to 219 sq ft
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How is the air in St. Paul in August?
Moderate on a typical day: median AQI 52 across 2019–2025, with 1.4% of August days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓46.1% of August days were Good (AQI 0–50), 52.5% Moderate (51–100).
- ✓3 days of 217 reached AQI 101+; the August peak was 173.
- ✓Best August: 2022; worst August: 2025.
Frequently asked questions
What is the air quality like in St. Paul in August?▾
Across 2019–2025, the median daily AQI in St. Paul in August was 52 (Moderate). 46.1% of days were Good, 52.5% Moderate, and 1.4% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is August a good time for outdoor exercise in St. Paul?▾
A typical August day in St. Paul is Moderate (median AQI 52): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 71 of August days (1.4%) 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. Paul's August air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 65.9% of August days in St. Paul. The highest August AQI recorded in 2019–2025 was 173 (Unhealthy), in 2025.
St. Paul August air quality, year by year
St. Paul August air quality by year (Minneapolis-St. Paul-Bloomington, MN-WI, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 31 | 49 | 0 | 70 | PM10 |
| 2020 | 31 | 51 | 0 | 77 | PM2.5 |
| 2021 | 31 | 51 | 0 | 94 | PM2.5 |
| 2022cleanest | 31 | 46 | 0 | 93 | PM2.5 |
| 2023 | 31 | 66 | 1 | 105 | PM2.5 |
| 2024 | 31 | 48 | 0 | 89 | PM2.5 |
| 2025worst | 31 | 56 | 2 | 173 | PM2.5 |
What August air means in St. Paul
A typical August day in St. Paul is Moderate (median AQI 52): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 71 of August days (1.4%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
August's median AQI of 52 is in line with St. Paul's whole-year median of 50, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median August AQI across every EPA metro area (104,152 metro-days, 2019–2025) is 45, so St. Paul runs above the national August norm; 1.4% of its August days topped AQI 100 versus 3.5% nationally (below average).
August is part of St. Paul's summer season (June, July, August); the summer page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in St. Paul
The latest EPA AirNow observation puts St. Paul's AQI at 25 (O3). The figures above are multi-year month statistics, not today's reading.
View current St. Paul air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Minneapolis-St. Paul-Bloomington, MN-WI), 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.