Milwaukee Air Quality in October
Across 2019–2025, Milwaukee's October air quality had a median AQI of 41 (Good) over 217 monitored days in the Milwaukee-Waukesha-West Allis, WI area. 2.3% of October days (5 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 68.2% of days. The cleanest October on record here was 2019 (median AQI 38, 0 days above 100) and the worst was 2023 (median 36, 2 days above 100, peak AQI 108).
- Good: 64.1%
- Moderate: 33.6%
- Unhealthy for Sensitive Groups: 2.3%
- 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 October?
Good on a typical day: median AQI 41 across 2019–2025, with 2.3% of October days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓64.1% of October days were Good (AQI 0–50), 33.6% Moderate (51–100).
- ✓5 days of 217 reached AQI 101+; the October peak was 112.
- ✓Best October: 2019; worst October: 2023.
Frequently asked questions
What is the air quality like in Milwaukee in October?▾
Across 2019–2025, the median daily AQI in Milwaukee in October was 41 (Good). 64.1% of days were Good, 33.6% Moderate, and 2.3% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is October a good time for outdoor exercise in Milwaukee?▾
A typical October day in Milwaukee sits in the Good range (median AQI 41), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 43 of October days (2.3%) reached AQI 101+ in 2019–2025.
Which pollutant causes Milwaukee's October air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 68.2% of October days in Milwaukee. The highest October AQI recorded in 2019–2025 was 112 (Unhealthy for Sensitive Groups), in 2023.
Milwaukee October air quality, year by year
Milwaukee October 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 |
|---|---|---|---|---|---|
| 2019cleanest | 31 | 38 | 0 | 62 | PM2.5 |
| 2020 | 31 | 44 | 0 | 62 | PM2.5 |
| 2021 | 31 | 42 | 0 | 80 | PM2.5 |
| 2022 | 31 | 53 | 1 | 103 | PM2.5 |
| 2023worst | 31 | 36 | 2 | 108 | PM2.5 |
| 2024 | 31 | 42 | 0 | 67 | PM2.5 |
| 2025 | 31 | 35 | 2 | 112 | O3 |
What October air means in Milwaukee
A typical October day in Milwaukee sits in the Good range (median AQI 41), so running, cycling and children's outdoor play are fine for everyone on most days; about 1 day in 43 of October days (2.3%) reached AQI 101+ in 2019–2025.
October's median AQI of 41 is below Milwaukee's whole-year median of 49, making it one of the area's cleaner periods. Nationally, the median October AQI across every EPA metro area (102,872 metro-days, 2019–2025) is 38, so Milwaukee runs in line with the national October norm; 2.3% of its October days topped AQI 100 versus 1.3% nationally (about the same).
October is part of Milwaukee's fall season (September, October, November); the fall page pools all three months.
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 month 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.