Bad Air Days in Eau Claire County, Wisconsin: 4 a Year
4 bad air days a year
About the middle of monitored US counties. Ranked 307 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly particles: smoke and dust (78% particle days).
When the bad days come in Eau Claire
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Most bad days here fall in June and July. 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 worst days on file
The worst recent year was 2023, with 18 bad days on 365 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2025-07-31 | 174 | PM2.5 |
| 2023-06-28 | 164 | PM2.5 |
| 2023-06-27 | 163 | PM2.5 |
| 2025-08-01 | 162 | PM2.5 |
| 2025-06-03 | 159 | PM2.5 |
The air on a normal day
Across 3,641 monitored days from 2016 to 2025, the air in Eau Claire County rated Good on 71% of them, close to the 72% typical of monitored counties, and Moderate on 28%. The median day sat at AQI 41; one day in ten went above 62.
The pollutant setting the AQI on an ordinary day here:
- fine particles (PM2.5)65%2,353 days
- ozone34%1,249 days
- coarse dust (PM10)1%39 days
Year by year
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 365 | 269 | 85 | 11 | 5 | 38 | 174 |
| 2024 | 366 | 299 | 66 | 1 | 0 | 38 | 142 |
| 2023 | 365 | 210 | 137 | 18 | 5 | 46 | 164 |
| 2022 | 365 | 268 | 97 | 0 | 0 | 41 | 81 |
| 2021 | 362 | 212 | 145 | 5 | 1 | 44 | 154 |
| 2020 | 366 | 256 | 110 | 0 | 0 | 42 | 93 |
| 2019 | 363 | 268 | 95 | 0 | 0 | 39 | 90 |
| 2018 | 365 | 244 | 120 | 1 | 0 | 44 | 129 |
| 2017 | 365 | 276 | 89 | 0 | 0 | 41 | 86 |
| 2016 | 359 | 268 | 91 | 0 | 0 | 40 | 84 |
| 2015 | 358 | 303 | 54 | 1 | 0 | 36 | 125 |
| 2014 | 354 | 279 | 75 | 0 | 0 | 37 | 94 |
| 2013 | 358 | 255 | 103 | 0 | 0 | 41 | 84 |
| 2012 | 303 | 210 | 91 | 2 | 0 | 43 | 115 |
| 2011 | 224 | 189 | 35 | 0 | 0 | 39 | 100 |
| 2010 | 42 | 26 | 16 | 0 | 0 | 40 | 94 |
*2025 may be a partial year in EPA's file.
Elsewhere in Wisconsin
- 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.