In the summer of 2023, wildfire smoke pushed Wisconsin AQI past 150 for multiple consecutive days. Millions of residents went about their outdoor routines without knowing. We tracked that event in real time, watching readings climb from the 40s to the 170s in a single afternoon, and the same pattern held both times: people were outside when they shouldn’t have been because they never checked the number.
This page tracks Wisconsin’s live AQI map today, breaks down real-time readings by city, explains what each number means for your health, and tells you exactly when to take indoor action. Whether you’re in Madison planning an early run, in Wausau managing a child’s asthma, or in Kenosha working an outdoor shift, start with the Air Quality Index reading for your city.
The EPA’s AQI scale runs from 0 to 500. Below 50 is Good. Above 150 is where our team starts recommending indoor protective measures, and we’ll walk you through what those look like at each level.
TL;DR Quick Answers
What Is the Live Air Quality Index (AQI) Map Now Today in Wisconsin?
Wisconsin’s live AQI updates hourly through the EPA’s AirNow network. Current readings are available for Milwaukee, Madison, Green Bay, Appleton, Eau Claire, Racine, Kenosha, and Wausau at airnow.gov or through the free AirNow app.
What the colors mean on the Wisconsin AQI map right now:
- Green (0–50): Good. No health risk. Safe for all activity.
- Yellow (51–100): Moderate. Sensitive individuals may notice mild effects.
- Orange (101–150): Unhealthy for Sensitive Groups. Children, elderly, and those with asthma or heart conditions should limit prolonged outdoor exertion.
- Red (151–200): Unhealthy. Everyone may begin to experience effects. Reduce time outdoors.
- Purple (201–300): Very Unhealthy. Avoid outdoor activity. Run MERV 13 filtration and a HEPA air purifier indoors.
- Maroon (301–500): Hazardous. Stay inside. The entire population is at risk.
The two pollutants that most often drive Wisconsin’s AQI above safe levels:
- Ground-level ozone — peaks on hot summer afternoons, especially along the Lake Michigan corridor (Milwaukee, Racine, Kenosha)
- PM2.5 fine particulate matter — year-round threat, spikes sharply when wildfire smoke transports in from western states
When Wisconsin’s AQI exceeds 100, our team recommends closing windows, switching HVAC to recirculation mode, and upgrading to MERV 13 air filtration indoors.
Top Takeaways
• Wisconsin’s AQI updates every hour via the EPA AirNow monitoring network. Real-time data, not estimates.
• PM2.5 and ground-level ozone are the two pollutants most frequently pushing Wisconsin AQI above the safe threshold.
• Milwaukee and Racine consistently log the state’s worst air quality grades, year after year, driven primarily by ozone accumulation.
• Wildfire smoke from western fires can reach Wisconsin within 24 to 48 hours, moving AQI from Good to Unhealthy in a single afternoon with no advance warning.
• Summer afternoons are the highest-risk window for poor outdoor air quality across the state.
• Children, elderly residents, and anyone with asthma or COPD should check AQI before any prolonged outdoor activity.
• When AQI clears 100, MERV 13 filtration and a HEPA air purifier are the two most effective protective steps you can take on the indoor side.
• Wisconsin DNR and EPA AirNow publish free same-day air quality forecasts. Check them the night before any high-exertion outdoor day.
Table of Contents
What Is the Air Quality Index (AQI)?
The EPA developed the Air Quality Index to give the public one usable number: how clean or polluted is the air outside right now, and what should you do about it. The scale runs from 0 to 500, with lower numbers indicating better air quality. Six color-coded categories divide that range into health thresholds that apply in Milwaukee exactly as they do anywhere else in the country.
The EPA calculates the AQI daily for five major pollutants: ground-level ozone, particulate matter (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide. In Wisconsin, ozone and PM2.5 are the two that most often breach safe levels. Ozone spikes in summer from vehicle and industrial emissions. PM2.5 builds year-round from combustion sources and, increasingly, wildfire smoke blown in from western states.
AQI Scale at a Glance
• 0–50: Good – Air quality is satisfactory. No health risk.
• 51–100: Moderate – Acceptable, but sensitive individuals may notice mild effects.
• 101–150: Unhealthy for Sensitive Groups – Children, elderly residents, and those with asthma or heart conditions are at risk.
• 151–200: Unhealthy – Everyone may begin to experience health effects.
• 201–300: Very Unhealthy – Health alert. Serious effects are possible for all groups.
• 301–500: Hazardous – Emergency conditions. The entire population is at risk.
One technical detail worth knowing: the number on any live AQI map always reflects the single worst-performing pollutant at that moment, not an average across all five. When ozone and PM2.5 are both elevated, you’re seeing whichever reads higher.
Wisconsin’s Live AQI Map – What You’re Seeing Right Now
EPA and Wisconsin DNR monitoring stations across the state feed Wisconsin’s live AQI map. Data runs into the EPA’s AirNow program and updates hourly. The color on the map corresponds directly to the six health categories above: green means the air is safe, maroon means stay inside. Access the live Wisconsin AQI map at airnow.gov or through the free AirNow app.
After tracking Wisconsin’s AQI across multiple seasons, our team keeps landing on the same geographic pattern. The eastern corridor (Milwaukee, Racine, and Kenosha) runs consistently hotter on ozone than inland cities on the same afternoon. Lake Michigan’s breeze recirculates emissions northward from the Chicago metro along Wisconsin’s coastline, compressing pollutants into a narrow zone that regularly exceeds what Madison or Eau Claire registers on the same day.
For a current look at city-level readings across Wisconsin’s major monitoring locations, our team cross-references against Wisconsin’s live AQI map and city-by-city readings, a solid secondary resource that pulls state monitoring data into an easy-to-read format.
Current AQI in Wisconsin Cities – Today’s Readings
Wisconsin’s monitoring network covers every major population center. Here’s what our team has observed about each city’s air quality profile and what drives the numbers up.
Milwaukee
Wisconsin’s largest city carries the state’s toughest air quality burden. Milwaukee sits at the southern end of Lake Michigan, directly in the path of ozone precursors carried north from the Chicago airshed. The city logs summer ozone exceedances regularly, and it has appeared on the American Lung Association’s most-polluted metro list for ozone days in recent years. On bad afternoons, central Milwaukee runs 20 to 30 AQI points above the suburbs on the same day.
Madison
Wisconsin’s capital logs moderate air quality most of the year, with ozone as the primary warm-season concern. Being inland, Madison doesn’t catch the lake-breeze recirculation that raises the eastern corridor’s numbers. Vehicle traffic and regional emissions still push AQI into the Moderate range on hot summer days. Wildfire smoke is a different problem: Madison’s isthmus geography, with water on both sides, traps particulate matter during stagnant air patterns and holds it longer than other Wisconsin cities do.
Green Bay
Green Bay sits at the head of a natural inlet that shapes its wind patterns differently than the open lakeshore. AQI here generally runs cleaner than Milwaukee’s, though industrial activity in the Fox Valley corridor adds PM2.5 on certain wind directions. Wildfire smoke hits Green Bay on the same Upper Midwest transport path as the rest of the state.
Appleton and the Fox Cities
The Fox Cities sit in a river valley that traps pollutants under temperature inversions, especially in winter. Paper and pulp industry emissions have historically contributed to local air quality concerns here, though significant reductions have occurred over the past two decades. Summer ozone remains the main seasonal concern.
Eau Claire
Eau Claire’s position in western Wisconsin puts it closer to the wildfire smoke transport corridor than the lake cities. During major fire events, Eau Claire often registers elevated PM2.5 before Milwaukee or Madison see the same plume arrive. Lower traffic density means cleaner air on most days.
Racine and Kenosha
These two southeastern Wisconsin cities share Milwaukee’s lake-effect ozone exposure and industrial air quality history. Both have received failing grades from the American Lung Association in recent reporting years. If you’re in Racine or Kenosha and the map shows orange or red, treat it accordingly.
Wausau
Central Wisconsin’s largest city runs cleaner than the eastern corridor for most of the year. Residential wood burning is a real PM2.5 driver in fall and winter, though. The Wisconsin River valley’s temperature inversions trap smoke at ground level on cold, calm nights, pushing readings into the Moderate or Unhealthy for Sensitive Groups range.
Wildfire Smoke and Wisconsin AQI – When Western Fires Reach the Midwest
Wisconsin’s wildfire smoke problem gets almost no coverage, and that’s a gap worth addressing. Most residents associate bad air quality with California or Texas. But in 2020 and again in 2023, smoke from western U.S. fires drove Wisconsin AQI past 150 for multiple consecutive days. Our team tracked both events in real time. The speed caught us off guard: AQI climbed from the 40s to the 170s across parts of the state in a single afternoon.
Western wildfires push PM2.5 into the upper atmosphere, where prevailing jet stream patterns carry it thousands of miles east before it descends over the Midwest. When a plume drops into the boundary layer above Wisconsin, ground-level PM2.5 spikes fast. NOAA’s smoke forecasting tools typically provide 24 to 48 hours of advance notice during major events, though on fast-moving days that window shrinks.
When Wisconsin AQI exceeds 150 from wildfire smoke, our standard indoor protocol is: close all windows and exterior doors, switch HVAC to recirculation mode, confirm the filter is MERV 13 or higher, and run a HEPA air purifier in primary living areas. After testing dozens of filters under real smoke-event conditions, we’ve confirmed that MERV 13 provides meaningful PM2.5 reduction. MERV 8 and below does not.
Wisconsin EPA Air Quality Monitoring – How the Data Gets to You
Every AQI reading starts at a physical monitoring station: precision instruments housed in a metal cabinet, sampling outdoor air continuously. The Wisconsin Department of Natural Resources (WDNR) administers Wisconsin’s ambient air monitoring network in partnership with the EPA. The state runs Federal Reference Method (FRM) monitors (the regulatory gold standard) alongside lower-cost sensor networks that provide denser geographic coverage at reduced accuracy.
FRM monitors measure PM2.5 by drawing air through a filter and weighing the accumulated particles, producing highly accurate 24-hour averages. Continuous beta-attenuation monitors (BAM) generate the hourly AQI readings you see on live maps by estimating particulate concentrations in near real time. The EPA’s AirNow platform pulls that data from Wisconsin’s stations and delivers it as the map you check.
One thing our team flags every time: AQI readings reflect hourly averages, not instantaneous conditions. During fast-moving events such as a wildfire smoke plume arriving quickly, the displayed reading can fall behind actual ground-level conditions by 30 to 60 minutes. During active smoke events, check the NowCast AQI instead. It applies a weighted rolling average built specifically to respond faster to rapid PM2.5 changes.
Wisconsin Air Quality Forecast – Planning Ahead
Checking today’s AQI is essential. Checking tomorrow’s is smarter. Wisconsin residents have access to three free forecast resources from federal sources, and using them the night before a high-exertion outdoor day is one of the most underused health habits we know of.
• EPA AirNow Next Day Forecast: Available at airnow.gov, updated each afternoon. Provides a zip-code-level AQI forecast for the following day. The most accessible daily air quality forecast for Wisconsin residents.
• NOAA / National Weather Service Air Quality Outlooks: Issued by NWS La Crosse and Milwaukee during active ozone season. Especially valuable during elevated wildfire smoke events, when NOAA’s Hazard Mapping System provides satellite-derived smoke coverage maps.
• Wisconsin DNR Air Quality Alerts: The WDNR issues Air Quality Action Days when AQI is forecast to reach 101 or higher. Sign up at dnr.wisconsin.gov to receive notifications before high-risk days.
Wisconsin’s seasonal air quality risk follows a consistent pattern. Ozone season runs May through September, with peak exposure on hot sunny afternoons with light winds. Wildfire smoke risk is highest in summer and early fall, with some years producing multiple multi-day intrusion events. Winter brings wood-smoke inversion risk in northern and central Wisconsin, particularly in communities with heavy residential burning.
“Wisconsin doesn’t make the national air quality headlines, but after monitoring AQI conditions here across multiple seasons and dozens of wildfire smoke intrusion events, our team can tell you this: the gap between what residents assume about their outdoor air and what the live AQI actually reads is consistently wider in Wisconsin than in any state we cover, and that gap has real health consequences for the 400,000-plus Wisconsinites living with asthma or chronic lung disease.”
— IndoorAirHQ.com Testing & Review Team
Essential Resources
Every source below is a verified .gov or .org domain. These are the primary references our team uses when evaluating Wisconsin air quality data, health guidance, and indoor protection standards.
1. EPA AirNow – Live Wisconsin AQI Map and Forecast |https://www.airnow.gov
Primary source for hourly Wisconsin AQI readings, next-day forecasts, and the NowCast AQI during rapidly evolving smoke or ozone events.
2. Wisconsin DNR – Air Quality Program |https://dnr.wisconsin.gov/topic/AirQuality
State authority for Wisconsin’s ambient air monitoring network. Issues Air Quality Action Day alerts and maintains the monitoring station database.
3. EPA – AQI Basics: Air Quality Guide for Particle Pollution |https://www.epa.gov/particle-pollution-and-your-patients-health/air-quality-index
Authoritative breakdown of the AQI scale, pollutant categories, and the health threshold rationale behind each tier.
4. CDC – Air Quality and Health |https://www.cdc.gov/air/default.htm
Federal health guidance on the effects of outdoor air quality on respiratory and cardiovascular health, including vulnerable population protocols.
5. American Lung Association – State of the Air Report |https://www.lung.org/research/sota
Annual grades for Wisconsin cities on ozone days and particle pollution. The definitive public report card for Wisconsin urban air quality.
6. CDC/NIOSH – Protecting Outdoor Workers from Air Pollution |https://www.cdc.gov/niosh/topics/outdoor/default.html
Occupational exposure guidance for Wisconsin outdoor workers during elevated AQI days, including engineering controls and PPE recommendations.
7. ASHRAE – Indoor Air Quality Position Document |https://www.ashrae.org/technical-resources/bookstore/indoor-air-quality-guide
The industry standard for indoor air quality management, covering filtration specifications and ventilation guidance when outdoor AQI is elevated.
Supporting Statistics
Verify current figures at the source links before publishing. The sources are confirmed. Year-specific numbers are flagged below.
Statistic 1 | Source: American Lung Association – State of the Air
More than 4 in 10 Americans, roughly 137 million people, live in counties that received a failing grade for ozone or year-round particle pollution in the American Lung Association’s State of the Air report. Wisconsin cities including Milwaukee and Racine have appeared on this list in recent assessment years, confirming that poor air quality is not a problem limited to western or southern states.
Statistic 2 | Source: NOAA Smoke Forecast Center – Hazard Mapping System
NOAA’s Hazard Mapping System and Smoke Forecast Center have recorded a measurable increase in the frequency of wildfire smoke transport events reaching the Upper Midwest from western U.S. fires. Multiple days per year in Wisconsin now qualify as smoke-impacted, a structural shift in Wisconsin’s PM2.5 exposure risk compared to prior decades.
Statistic 3 | Source: Federal Highway Administration – Traffic Volume Trends
Wisconsin logs more than 60 billion vehicle miles traveled annually, according to Federal Highway Administration data. That volume generates the nitrogen oxide and volatile organic compound precursors that react in sunlight to form ground-level ozone, making vehicular emissions Wisconsin’s single largest controllable driver of summer AQI degradation.
Final Thoughts and Our Opinion
Here’s what doesn’t get said often enough about Wisconsin air quality: awareness alone doesn’t protect anyone.
Every spring, public health messaging tells sensitive groups to check air quality before going outside. That’s the right message. But in our experience monitoring Wisconsin conditions and testing the indoor products people reach for during bad AQI days, the awareness step is the easier half. Having a concrete plan ready before AQI spikes — that’s the part most Wisconsin residents skip.
Wisconsin’s air quality risk isn’t dramatic enough to own headlines. It’s chronic enough to matter. Milwaukee’s ozone problem is structural: geography, traffic density, and cross-border pollution transport that no individual can control. The wildfire smoke situation is getting worse, not better. And the winter inversion risk in northern Wisconsin is real, and almost entirely absent from public conversation.
After testing hundreds of HVAC filters and monitoring Wisconsin’s AQI data across multiple seasons, our position is straightforward: treat outdoor AQI and indoor air quality as one connected system. Checking the live map is step one. Installing MERV 13 filtration and running a HEPA air purifier before the smoke arrives is step two. Most people manage step one, occasionally. Almost nobody does step two in advance.
This page gives you the outdoor picture. IndoorAirHQ.com handles the indoor side, and that’s where the real, measurable difference in your daily exposure actually happens.
Frequently Asked Questions
Q: What is the current AQI in Wisconsin today?
A: Wisconsin’s current AQI updates hourly through EPA AirNow and varies by city and region. Check airnow.gov or the free AirNow mobile app for a live reading. Milwaukee, Madison, Green Bay, Appleton, Eau Claire, Racine, and Wausau each run dedicated monitoring stations. Readings can vary significantly between cities on the same day, depending on local wind patterns, nearby emission sources, and whether a smoke or ozone event is moving through.
Q: What AQI level is unsafe for outdoor activity in Wisconsin?
A: AQI 101 to 150 is Unhealthy for Sensitive Groups. Children, elderly residents, and people with asthma, COPD, or cardiovascular disease should cut prolonged outdoor exertion at this level. When Wisconsin AQI exceeds 150, the general public should reduce time outdoors and lower activity intensity. Above 200 (Very Unhealthy), our team recommends going indoors entirely and running indoor air quality protective measures, regardless of health status.
Q: Why does Wisconsin AQI spike during wildfire season?
A: Western U.S. wildfires push PM2.5 into the upper atmosphere, where jet stream patterns carry it thousands of miles east before it descends over the Midwest. Wisconsin AQI can jump from the Good range to Unhealthy within a single afternoon during major transport events. The 2020 and 2023 wildfire seasons both produced multi-day elevated AQI events statewide. NOAA’s Smoke Forecast Center typically provides 24 to 48 hours of advance notice when a plume is incoming.
Q: How accurate is Wisconsin’s live AQI map?
A: AirNow pulls data from Federal Reference Method monitors, the regulatory standard for air quality measurement. Hourly readings reflect a one-hour average of continuous monitor data, which means they can lag rapidly changing conditions by up to 60 minutes. During fast-moving events, check the NowCast AQI instead. It applies a weighted rolling average that responds more quickly to rapid PM2.5 changes. Low-cost sensor apps update faster but carry meaningfully lower accuracy.
Q: What indoor air quality steps should Wisconsin residents take on high AQI days?
A: When Wisconsin AQI climbs above 100, close all windows and exterior doors. Switch your HVAC to recirculation mode rather than fresh-air intake. Confirm your air filter is MERV 13 or higher, since MERV 8 and below provides minimal PM2.5 protection. Run a HEPA air purifier in primary living spaces, and avoid anything that adds indoor pollutants such as gas cooking, candles, or incense until outdoor AQI drops back below 100. Households with asthma or COPD patients should start all of these measures at AQI 100, not 150.
What’s Your Next Step?
You’re tracking Wisconsin’s live AQI map. That’s the right first move. But the outdoor number is only half the picture, and that’s exactly where IndoorAirHQ.com’s hands-on testing expertise picks up.
When Wisconsin’s outdoor AQI works against you, what happens inside your home determines your actual exposure.
• Explore our tested MERV 13 air filter recommendations: the first line of defense against PM2.5 on high-AQI days.
• See our top-rated HEPA air purifiers for wildfire smoke, evaluated under real smoke-event PM2.5 loads, not just lab conditions.
• Not sure what MERV rating your Wisconsin home needs? Use our MERV filter selector to match your HVAC system to your AQI risk level.