Bad Air Days in Monroe County, Wisconsin: 3 a Year
3 bad air days a year
About the middle of monitored US counties. Ranked 328 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly particles: smoke and dust (100% particle days).
Which months to watch
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Most bad days here fall in June and August and July. Averaged over 2016 to 2025.
What to buy, and what not to
- Particles (wildfire smoke, dust) cause enough bad days here to matter. A HEPA purifier sized to your bedroom removes them; run it with windows shut on bad days.
The record for Monroe
The worst recent year was 2025, with 9 bad days on 305 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2023-06-28 | 173 | PM2.5 |
| 2025-07-31 | 165 | PM2.5 |
| 2025-07-30 | 159 | PM2.5 |
| 2023-06-27 | 158 | PM2.5 |
| 2023-06-04 | 150 | PM2.5 |
Most days, not the worst ones
Across 1,587 monitored days from 2021 to 2025, the air in Monroe County rated Good on 77% of them, more often than the 72% typical of monitored counties, and Moderate on 22%. The median day sat at AQI 32; one day in ten went above 57.
The pollutant setting the AQI on an ordinary day here:
- fine particles (PM2.5)100%1,587 days
Monroe County by year
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 305 | 206 | 90 | 9 | 2 | 36 | 165 |
| 2024 | 288 | 258 | 30 | 0 | 0 | 23 | 90 |
| 2023 | 365 | 252 | 108 | 5 | 2 | 37 | 173 |
| 2022 | 364 | 295 | 68 | 1 | 0 | 32 | 132 |
| 2021 | 265 | 216 | 49 | 0 | 0 | 32 | 94 |
| 2013 | 61 | 61 | 0 | 0 | 0 | 13 | 44 |
| 2012 | 36 | 36 | 0 | 0 | 0 | 10 | 33 |
*2025 may be a partial year in EPA's file.
Wisconsin compared
- Sheboygan County16/yr
- Racine County15/yr
- Kenosha County12/yr
- Ozaukee County9/yr
- Milwaukee County8/yr
- Manitowoc County7/yr
- Door County7/yr
- Walworth County6/yr
How this is counted
A bad air day is a day the county's daily AQI from EPA AirData went above 100, the level where EPA tells children, older adults and people with asthma or heart disease to cut back outdoors. Monitors do not run every day, so yearly counts are scaled to 365 days. This is the record, not today's air: for that, check AirNow. More on the method in how the county numbers are made, on the AQI 100 line in what counts as a bad air day.