St. Paul Air Quality in May
Across 2019–2025, St. Paul's May air quality had a median AQI of 49 (Good) over 217 monitored days in the Minneapolis-St. Paul-Bloomington, MN-WI area. 4.1% of May days (9 of 217) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 63.6% of days. The cleanest May on record here was 2019 (median AQI 42, 0 days above 100) and the worst was 2023 (median 61, 7 days above 100, peak AQI 154).
- Good: 53.9%
- Moderate: 41.9%
- Unhealthy for Sensitive Groups: 3.2%
- Unhealthy or worse: 0.9%
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 May?
Good on a typical day: median AQI 49 across 2019–2025, with 4.1% of May days above AQI 100. Ground-level ozone is the main driver.
- ✓53.9% of May days were Good (AQI 0–50), 41.9% Moderate (51–100).
- ✓9 days of 217 reached AQI 101+; the May peak was 154.
- ✓Best May: 2019; worst May: 2023.
Frequently asked questions
What is the air quality like in St. Paul in May?▾
Across 2019–2025, the median daily AQI in St. Paul in May was 49 (Good). 53.9% of days were Good, 41.9% Moderate, and 4.1% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is May a good time for outdoor exercise in St. Paul?▾
A typical May day in St. Paul sits in the Good range (median AQI 49), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 24 of May days (4.1%) reached AQI 101+ in 2019–2025.
Which pollutant causes St. Paul's May air quality problems?▾
Ground-level ozone set the daily AQI on 63.6% of May days in St. Paul. The highest May AQI recorded in 2019–2025 was 154 (Unhealthy), in 2023.
St. Paul May air quality, year by year
St. Paul May 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 |
|---|---|---|---|---|---|
| 2019cleanest | 31 | 42 | 0 | 77 | O3 |
| 2020 | 31 | 48 | 0 | 60 | O3 |
| 2021 | 31 | 44 | 0 | 80 | O3 |
| 2022 | 31 | 48 | 0 | 77 | O3 |
| 2023worst | 31 | 61 | 7 | 154 | O3 |
| 2024 | 31 | 50 | 2 | 152 | O3 |
| 2025 | 31 | 52 | 0 | 97 | O3 |
What May air means in St. Paul
A typical May day in St. Paul sits in the Good range (median AQI 49), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 24 of May days (4.1%) reached AQI 101+ in 2019–2025.
May's median AQI of 49 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 May AQI across every EPA metro area (104,064 metro-days, 2019–2025) is 44, so St. Paul runs above the national May norm; 4.1% of its May days topped AQI 100 versus 1.3% nationally (above average).
May is part of St. Paul's spring season (March, April, May); the spring 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.