Milwaukee Air Quality in Fall
Across 2019–2025, Milwaukee's fall (September–November) air quality had a median AQI of 44 (Good) over 637 monitored days in the Milwaukee-Waukesha-West Allis, WI area. 1.3% of fall days (8 of 637) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 69.4% of days. The cleanest fall on record here was 2020 (median AQI 45, 0 days above 100) and the worst was 2023 (median 45, 2 days above 100, peak AQI 108).
- Good: 60.1%
- Moderate: 38.6%
- Unhealthy for Sensitive Groups: 1.3%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Milwaukee
Today's main pollutant in Milwaukee is ground-level ozone (AQI 32). Important: standard HEPA filters do NOT remove ozone — only a purifier with a substantial activated-carbon bed adsorbs it. The biggest wins are cutting indoor sources (gas appliances, certain "ionizer" purifiers) and ventilating when outdoor ozone is low (early morning). A high-carbon unit helps with the gases and VOCs that linger indoors.
Recommended: Levoit Core 300 — True HEPA + activated carbon · CADR ~141 CFM · rooms up to 219 sq ft
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How is the air in Milwaukee in fall?
Good on a typical day: median AQI 44 across 2019–2025, with 1.3% of fall days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓60.1% of fall days were Good (AQI 0–50), 38.6% Moderate (51–100).
- ✓8 days of 637 reached AQI 101+; the fall peak was 115.
- ✓Cleanest month: November; worst month: October.
Frequently asked questions
What is the air quality like in Milwaukee in fall?▾
Across 2019–2025, the median daily AQI in Milwaukee in fall was 44 (Good). 60.1% of days were Good, 38.6% Moderate, and 1.3% reached Unhealthy for Sensitive Groups or worse, based on 637 monitored days in EPA's Air Quality System.
Is fall a good time for outdoor exercise in Milwaukee?▾
A typical fall day in Milwaukee sits in the Good range (median AQI 44), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 77 of fall days (1.3%) reached AQI 101+ in 2019–2025.
Which pollutant causes Milwaukee's fall air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 69.4% of fall days in Milwaukee. The highest fall AQI recorded in 2019–2025 was 115 (Unhealthy for Sensitive Groups), in 2023.
Milwaukee fall air quality, year by year
Milwaukee fall air quality by year (Milwaukee-Waukesha-West Allis, WI, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 91 | 43 | 1 | 105 | PM2.5 |
| 2020cleanest | 91 | 45 | 0 | 80 | PM2.5 |
| 2021 | 91 | 47 | 0 | 80 | PM2.5 |
| 2022 | 91 | 50 | 1 | 103 | PM2.5 |
| 2023worst | 91 | 45 | 2 | 108 | PM2.5 |
| 2024 | 91 | 42 | 2 | 115 | PM2.5 |
| 2025 | 91 | 40 | 2 | 112 | PM2.5 |
What fall air means in Milwaukee
A typical fall day in Milwaukee sits in the Good range (median AQI 44), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 77 of fall days (1.3%) reached AQI 101+ in 2019–2025.
Fall's median AQI of 44 is below Milwaukee's whole-year median of 49, making it one of the area's cleaner periods. Nationally, the median Fall AQI across every EPA metro area (296,275 metro-days, 2019–2025) is 40, so Milwaukee runs above the national Fall norm; 1.3% of its Fall days topped AQI 100 versus 1.5% nationally (about the same).
Within the season, November is the cleanest month (median AQI 46, 0.0% of days above 100) and October the worst (median 41, 2.3% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Milwaukee
The latest EPA AirNow observation puts Milwaukee's AQI at 32 (O3). The figures above are multi-year season statistics, not today's reading.
View current Milwaukee air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Milwaukee-Waukesha-West Allis, WI), 2019–2025. Daily AQI per CBSA is the highest AQI reported by any monitor in the area that day; the defining parameter is the pollutant that set it. Month and season statistics pool every such day in the period across all years listed. Retrieved 2026-09-09.