Metro area air quality · 2024
Winona, MN
Median AQI 20 (Good). 93.4% of monitored days rated Good across this metro's EPA monitoring network.
- 20
- Median AQI
- 93.4%
- Good-air days
- 0
- Unhealthy days
- 91%
- Cleaner than US metros
Aggregated from EPA Air Quality System (2024), 122 monitored days. EPA AQS → · NOAA →
Insights: Winona, MN metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 20 over 122 measured days in 2024, which corresponds to a Good band and a Excellent metro-wide health grade. The monitored-day split lands at 114 Good days (93%), 8 Moderate (7%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 41 while the highest single-day reading hit 63 (Moderate). Metro residents averaged roughly 28.0 clean-air days per 30-day window across the reporting year.
Across the 2020–2024 trend window, good days shifted by +2 and the median AQI moved -2 points, which classifies the multi-year trajectory as stable. The metro avoided any Unhealthy-tier days entirely, an outcome that typically reflects favorable wind patterns, lower industrial density, or effective regional emission controls. Metros with comparable AQI profiles include Aberdeen, WA (96.5% good, AQI 20); Pullman, WA (84.7% good, AQI 20); Bremerton-Silverdale, WA (97.2% good, AQI 19).
Air Quality Summary
Median AQI
20
Good
Good Days
93.4%
114 of 122 days
Max AQI
63
Moderate
Health Grade
Excellent
90th pct: 41
AQI Day Breakdown (2024)
Distribution of 122 monitored days across EPA AQI categories.
Good
114
93%
Moderate
8
7%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Health Impact Assessment
The Winona, MN metro area's air quality is rated Excellent based on 93.4% good air days. No unhealthy air days were recorded in 2024.
Air quality is generally acceptable. Unusually sensitive people should monitor real-time conditions at AirNow.gov during high-pollution events.
How does the Winona, MN metro compare?
How Winona, MN compares
5-Year Air Quality Trend
Air quality is stable in the Winona, MN metro. Best year: 2024 (114 good days).
| Year | Good | Moderate | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|
| 2020 | 112 | 7 | 0 | 22 | 57 |
| 2021 | 101 | 15 | 0 | 24 | 80 |
| 2022 | 113 | 8 | 0 | 22 | 65 |
| 2023 | 95 | 22 | 1 | 28 | 169 |
| 2024 | 114 | 8 | 0 | 20 | 63 |
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Frequently Asked Questions
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What is the 90th percentile AQI for Winona, MN? ▼
How does Winona, MN compare to other metro areas? ▼
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset, 2020–2024. The AQS collects ambient air monitoring data from state, local, and tribal monitoring agencies across the United States.
Metrics: Air Quality Index (AQI) is calculated using EPA-standard breakpoints for six criteria pollutants: PM2.5, PM10, Ozone, NO2, CO, and SO2. Median AQI, max AQI, and 90th percentile AQI are computed from daily measurements. Good days percentage reflects days with AQI 0–50.
Coverage: 501 metro areas (Core Based Statistical Areas). Only metros with active monitoring stations are included. Unmonitored areas are not represented.
Read our methodology , how this data is sourced, computed, and verified.
Source: U.S. EPA, AirNow / AQS Air Quality Index readings and pollutant concentrations · 2025