EnviroNearby

Sheboygan County, Wisconsin air quality history

Daily Air Quality Index summaries from EPA monitors in Sheboygan, Wisconsin, 1980–2025.

79%
Good days in 2025
41
Median daily AQI, 2025
7
Days above 100 in 2025
199
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Sheboygan, Wisconsin on 199 days. 157 of those days (79%) were in the Good range, and the median daily AQI was 41. That median is higher than the typical monitored county in Wisconsin (median 38 across 29 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 199 days. Across the years with fuller monitoring, the share of Good days fell: an average of 85% in 1980–1982 versus 75% in 2023–2025.

EPA did not report an AQI for every day of 2025 here (199 of 365 days). Figures describe monitored days only; seasonal monitoring (for example, ozone measured only in warmer months) can make a county look cleaner or dirtier than a full-year record would.

How the days broke down each year

Each bar is one year. The colored segments show the share of monitored days that fell in each AQI category.

Share of monitored days in each AQI category, by year0%25%50%75%100%1980: Good 289 of 356 days1980: Moderate 34 of 356 days1980: Unhealthy for Sensitive Groups 13 of 356 days1980: Unhealthy 16 of 356 days1980: Very Unhealthy 4 of 356 days19801981: Good 282 of 326 days1981: Moderate 26 of 326 days1981: Unhealthy for Sensitive Groups 13 of 326 days1981: Unhealthy 4 of 326 days1981: Very Unhealthy 1 of 326 days1982: Good 270 of 314 days1982: Moderate 29 of 314 days1982: Unhealthy for Sensitive Groups 9 of 314 days1982: Unhealthy 6 of 314 days1983: Good 260 of 312 days1983: Moderate 20 of 312 days1983: Unhealthy for Sensitive Groups 14 of 312 days1983: Unhealthy 12 of 312 days1983: Very Unhealthy 6 of 312 days1984: Good 303 of 351 days1984: Moderate 22 of 351 days1984: Unhealthy for Sensitive Groups 11 of 351 days1984: Unhealthy 13 of 351 days1984: Very Unhealthy 2 of 351 days1985: Good 300 of 346 days1985: Moderate 31 of 346 days1985: Unhealthy for Sensitive Groups 12 of 346 days1985: Unhealthy 3 of 346 days19851986: Good 317 of 358 days1986: Moderate 27 of 358 days1986: Unhealthy for Sensitive Groups 10 of 358 days1986: Unhealthy 4 of 358 days1987: Good 286 of 356 days1987: Moderate 30 of 356 days1987: Unhealthy for Sensitive Groups 18 of 356 days1987: Unhealthy 13 of 356 days1987: Very Unhealthy 9 of 356 days1988: Good 289 of 364 days1988: Moderate 30 of 364 days1988: Unhealthy for Sensitive Groups 19 of 364 days1988: Unhealthy 11 of 364 days1988: Very Unhealthy 15 of 364 days1989: Good 308 of 365 days1989: Moderate 37 of 365 days1989: Unhealthy for Sensitive Groups 14 of 365 days1989: Unhealthy 5 of 365 days1989: Very Unhealthy 1 of 365 days1990: Good 325 of 362 days1990: Moderate 26 of 362 days1990: Unhealthy for Sensitive Groups 8 of 362 days1990: Unhealthy 3 of 362 days19901991: Good 151 of 216 days1991: Moderate 31 of 216 days1991: Unhealthy for Sensitive Groups 19 of 216 days1991: Unhealthy 10 of 216 days1991: Very Unhealthy 5 of 216 days1992: Good 147 of 179 days1992: Moderate 20 of 179 days1992: Unhealthy for Sensitive Groups 12 of 179 days1993: Good 149 of 180 days1993: Moderate 23 of 180 days1993: Unhealthy for Sensitive Groups 8 of 180 days1994: Good 149 of 178 days1994: Moderate 17 of 178 days1994: Unhealthy for Sensitive Groups 10 of 178 days1994: Unhealthy 1 of 178 days1994: Very Unhealthy 1 of 178 days1995: Good 134 of 180 days1995: Moderate 24 of 180 days1995: Unhealthy for Sensitive Groups 14 of 180 days1995: Unhealthy 7 of 180 days1995: Very Unhealthy 1 of 180 days19951996: Good 148 of 178 days1996: Moderate 19 of 178 days1996: Unhealthy for Sensitive Groups 8 of 178 days1996: Unhealthy 2 of 178 days1996: Very Unhealthy 1 of 178 days1997: Good 125 of 165 days1997: Moderate 26 of 165 days1997: Unhealthy for Sensitive Groups 9 of 165 days1997: Unhealthy 3 of 165 days1997: Very Unhealthy 2 of 165 days1998: Good 129 of 184 days1998: Moderate 33 of 184 days1998: Unhealthy for Sensitive Groups 16 of 184 days1998: Unhealthy 6 of 184 days1999: Good 125 of 181 days1999: Moderate 28 of 181 days1999: Unhealthy for Sensitive Groups 16 of 181 days1999: Unhealthy 12 of 181 days2000: Good 143 of 184 days2000: Moderate 32 of 184 days2000: Unhealthy for Sensitive Groups 5 of 184 days2000: Unhealthy 4 of 184 days20002001: Good 118 of 184 days2001: Moderate 43 of 184 days2001: Unhealthy for Sensitive Groups 10 of 184 days2001: Unhealthy 10 of 184 days2001: Very Unhealthy 3 of 184 days2002: Good 117 of 184 days2002: Moderate 34 of 184 days2002: Unhealthy for Sensitive Groups 15 of 184 days2002: Unhealthy 15 of 184 days2002: Very Unhealthy 3 of 184 days2003: Good 125 of 184 days2003: Moderate 40 of 184 days2003: Unhealthy for Sensitive Groups 15 of 184 days2003: Unhealthy 3 of 184 days2003: Very Unhealthy 1 of 184 days2004: Good 152 of 184 days2004: Moderate 21 of 184 days2004: Unhealthy for Sensitive Groups 11 of 184 days2005: Good 140 of 202 days2005: Moderate 34 of 202 days2005: Unhealthy for Sensitive Groups 17 of 202 days2005: Unhealthy 9 of 202 days2005: Very Unhealthy 2 of 202 days20052006: Good 163 of 217 days2006: Moderate 40 of 217 days2006: Unhealthy for Sensitive Groups 11 of 217 days2006: Unhealthy 2 of 217 days2006: Very Unhealthy 1 of 217 days2007: Good 134 of 204 days2007: Moderate 46 of 204 days2007: Unhealthy for Sensitive Groups 18 of 204 days2007: Unhealthy 6 of 204 days2008: Good 145 of 184 days2008: Moderate 32 of 184 days2008: Unhealthy for Sensitive Groups 7 of 184 days2009: Good 167 of 195 days2009: Moderate 24 of 195 days2009: Unhealthy for Sensitive Groups 3 of 195 days2009: Unhealthy 1 of 195 days2010: Good 146 of 189 days2010: Moderate 31 of 189 days2010: Unhealthy for Sensitive Groups 9 of 189 days2010: Unhealthy 3 of 189 days20102011: Good 150 of 189 days2011: Moderate 26 of 189 days2011: Unhealthy for Sensitive Groups 11 of 189 days2011: Unhealthy 1 of 189 days2011: Very Unhealthy 1 of 189 days2012: Good 131 of 195 days2012: Moderate 28 of 195 days2012: Unhealthy for Sensitive Groups 28 of 195 days2012: Unhealthy 8 of 195 days2013: Good 125 of 187 days2013: Moderate 52 of 187 days2013: Unhealthy for Sensitive Groups 10 of 187 days2014: Good 161 of 201 days2014: Moderate 35 of 201 days2014: Unhealthy for Sensitive Groups 5 of 201 days2015: Good 154 of 198 days2015: Moderate 33 of 198 days2015: Unhealthy for Sensitive Groups 10 of 198 days2015: Unhealthy 1 of 198 days20152016: Good 166 of 203 days2016: Moderate 25 of 203 days2016: Unhealthy for Sensitive Groups 10 of 203 days2016: Unhealthy 2 of 203 days2017: Good 192 of 245 days2017: Moderate 40 of 245 days2017: Unhealthy for Sensitive Groups 13 of 245 days2018: Good 186 of 239 days2018: Moderate 42 of 239 days2018: Unhealthy for Sensitive Groups 9 of 239 days2018: Unhealthy 2 of 239 days2019: Good 180 of 206 days2019: Moderate 24 of 206 days2019: Unhealthy for Sensitive Groups 2 of 206 days2020: Good 170 of 207 days2020: Moderate 31 of 207 days2020: Unhealthy for Sensitive Groups 4 of 207 days2020: Unhealthy 2 of 207 days20202021: Good 164 of 208 days2021: Moderate 39 of 208 days2021: Unhealthy for Sensitive Groups 5 of 208 days2022: Good 172 of 203 days2022: Moderate 24 of 203 days2022: Unhealthy for Sensitive Groups 6 of 203 days2022: Unhealthy 1 of 203 days2023: Good 132 of 203 days2023: Moderate 53 of 203 days2023: Unhealthy for Sensitive Groups 16 of 203 days2023: Unhealthy 1 of 203 days2023: Very Unhealthy 1 of 203 days2024: Good 166 of 205 days2024: Moderate 30 of 205 days2024: Unhealthy for Sensitive Groups 7 of 205 days2024: Unhealthy 2 of 205 days2025: Good 157 of 199 days2025: Moderate 35 of 199 days2025: Unhealthy for Sensitive Groups 6 of 199 days2025: Unhealthy 1 of 199 days2025
  • Good
  • Moderate
  • Unhealthy for Sensitive Groups
  • Unhealthy
  • Very Unhealthy
  • Hazardous

Typical and high-end AQI over time

The median is the middle day of the year. The 90th percentile is the level that only the highest 10% of days exceeded.

Median and 90th-percentile daily AQI, by year0501001501980: 90th percentile AQI 971981: 90th percentile AQI 651982: 90th percentile AQI 671983: 90th percentile AQI 1011984: 90th percentile AQI 841985: 90th percentile AQI 611986: 90th percentile AQI 581987: 90th percentile AQI 1191988: 90th percentile AQI 1261989: 90th percentile AQI 771990: 90th percentile AQI 511991: 90th percentile AQI 1221992: 90th percentile AQI 871993: 90th percentile AQI 801994: 90th percentile AQI 901995: 90th percentile AQI 1121996: 90th percentile AQI 741997: 90th percentile AQI 931998: 90th percentile AQI 1051999: 90th percentile AQI 1292000: 90th percentile AQI 842001: 90th percentile AQI 1192002: 90th percentile AQI 1502003: 90th percentile AQI 1012004: 90th percentile AQI 772005: 90th percentile AQI 1262006: 90th percentile AQI 902007: 90th percentile AQI 1082008: 90th percentile AQI 742009: 90th percentile AQI 612010: 90th percentile AQI 872011: 90th percentile AQI 772012: 90th percentile AQI 1262013: 90th percentile AQI 872014: 90th percentile AQI 712015: 90th percentile AQI 802016: 90th percentile AQI 672017: 90th percentile AQI 712018: 90th percentile AQI 842019: 90th percentile AQI 612020: 90th percentile AQI 742021: 90th percentile AQI 742022: 90th percentile AQI 742023: 90th percentile AQI 1002024: 90th percentile AQI 742025: 90th percentile AQI 771980: Median AQI 331981: Median AQI 291982: Median AQI 321983: Median AQI 311984: Median AQI 311985: Median AQI 311986: Median AQI 311987: Median AQI 321988: Median AQI 341989: Median AQI 311990: Median AQI 301991: Median AQI 341992: Median AQI 341993: Median AQI 361994: Median AQI 391995: Median AQI 411996: Median AQI 401997: Median AQI 411998: Median AQI 431999: Median AQI 412000: Median AQI 422001: Median AQI 442002: Median AQI 442003: Median AQI 442004: Median AQI 372005: Median AQI 422006: Median AQI 412007: Median AQI 442008: Median AQI 422009: Median AQI 372010: Median AQI 412011: Median AQI 412012: Median AQI 422013: Median AQI 432014: Median AQI 412015: Median AQI 402016: Median AQI 392017: Median AQI 412018: Median AQI 432019: Median AQI 382020: Median AQI 392021: Median AQI 412022: Median AQI 402023: Median AQI 452024: Median AQI 402025: Median AQI 411980198519901995200020052010201520202025
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2025

On each monitored day, the AQI reflects whichever measured pollutant had the highest index. This counts how many days each pollutant set the AQI. A pollutant that was not measured here cannot appear.

PollutantDays as main pollutantShare of monitored days
Ozone199100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20251991573561004177156Ozone
20242051663072004074166Ozone
2023203132531611045100207Ozone
20222031722461004074177Ozone
20212081643950004174126Ozone
20202071703142003974159Ozone
20192061802420003861108Ozone
20182391864292004384185Ozone
201724519240130004171129Ozone
201620316625102003967164Ozone
201519815433101004080159Ozone
20142011613550004171129Ozone
201318712552100004387140Ozone
2012195131282880042126192Ozone
201118915026111104177206Ozone
20101891463193004187166Ozone
20091951672431003761174Ozone
20081841453270004274129Ozone
2007204134461860044108166Ozone
200621716340112104190204Ozone
2005202140341792042126205Ozone
200418415221110003777140Ozone
2003184125401531044101208Ozone
20021841173415153044150219Ozone
20011841184310103044119212Ozone
20001841433254004284200Ozone
19991811252816120041129200Ozone
1998184129331660043105200Ozone
19971651252693204193220Ozone
19961781481982104074201Ozone
1995180134241471041112206Ozone
199417814917101103990230Ozone
19931801492380003680143Ozone
199217914720120003487150Ozone
19912161513119105034122243Ozone
19903623252683003051166Ozone
198936530837145103177202Ozone
198836428930191115034126237Ozone
19873562863018139032119271Ozone
198635831727104003158192Ozone
198534630031123003161172Ozone
1984351303221113203184215Ozone
19833122602014126031101264Ozone
19823142702996003267192Ozone
198132628226134102965205Ozone
1980356289341316403397212Ozone

What this data can and can’t tell you

It is a county-level summary. EPA reports one AQI per day for the county, based on the monitors operating there. Air at a particular street, school or home can differ, especially near roads, industry or wildfire smoke.

It is not a health assessment. The AQI is EPA’s scale for communicating daily air quality. A county’s history can’t tell you what the health risk is for any particular person. For daily conditions and health guidance, see AirNow.

Rules change over time. EPA has revised AQI breakpoints, most recently for fine particles in 2024, so some year-to-year change can reflect the scale rather than the air.

Counties in Wisconsin with a similar median AQI in 2025

All monitored counties in Wisconsin

Source: U.S. EPA AirData, “Annual AQI by County” files for 1980–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem