Bad Air Days in Forest County, Wisconsin: 3 a Year
3 bad air days a year
About the middle of monitored US counties. Ranked 348 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly particles: smoke and dust (84% particle days).
When the bad days come in Forest
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Most bad days here fall in June and August and July and May. Averaged over 2016 to 2025.
Is a purifier worth it here?
- Bad air days are rare here. A standard furnace filter is enough; no purifier needed for outdoor air.
- On the odd bad day, check AirNow and keep windows shut.
The record for Forest
In 2000 to 2009 this county averaged 2 bad days a year; in 2016 to 2025, 3. Not much has changed. The worst recent year was 2025, with 14 bad days on 361 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2025-07-30 | 182 | PM2.5 |
| 2023-06-28 | 178 | PM2.5 |
| 2025-07-31 | 173 | PM2.5 |
| 2023-06-26 | 171 | PM2.5 |
| 2021-08-26 | 165 | PM2.5 |
Most days, not the worst ones
Across 3,620 monitored days from 2016 to 2025, the air in Forest County rated Good on 83% of them, more often than the 72% typical of monitored counties, and Moderate on 16%. The median day sat at AQI 37; one day in ten went above 56.
The pollutant setting the AQI on an ordinary day here:
- ozone70%2,528 days
- fine particles (PM2.5)30%1,092 days
Forest County by year
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 361 | 271 | 76 | 14 | 7 | 39 | 182 |
| 2024 | 364 | 313 | 50 | 1 | 1 | 37 | 153 |
| 2023 | 363 | 252 | 99 | 12 | 3 | 42 | 178 |
| 2022 | 363 | 321 | 42 | 0 | 0 | 37 | 77 |
| 2021 | 361 | 282 | 75 | 4 | 1 | 38 | 165 |
| 2020 | 366 | 311 | 55 | 0 | 0 | 36 | 93 |
| 2019 | 363 | 308 | 55 | 0 | 0 | 36 | 97 |
| 2018 | 365 | 300 | 65 | 0 | 0 | 38 | 93 |
| 2017 | 364 | 327 | 37 | 0 | 0 | 36 | 74 |
| 2016 | 350 | 325 | 24 | 1 | 0 | 34 | 101 |
| 2015 | 362 | 318 | 43 | 1 | 0 | 35 | 102 |
| 2014 | 364 | 314 | 50 | 0 | 0 | 36 | 87 |
| 2013 | 362 | 300 | 62 | 0 | 0 | 38 | 84 |
| 2012 | 364 | 306 | 53 | 5 | 0 | 36 | 140 |
| 2011 | 365 | 304 | 60 | 1 | 0 | 37 | 115 |
| 2010 | 362 | 328 | 34 | 0 | 0 | 36 | 93 |
*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.