Metro area air quality · 2025
Milwaukee-Waukesha-West Allis, WI
Median AQI 45 (Good). 60.0% of monitored days rated Good across this metro's EPA monitoring network.
- 45
- Median AQI
- 60.0%
- Good-air days
- 3
- Unhealthy days
- 25%
- Cleaner than US metros
Milwaukee-Waukesha-West Allis, WI posted a 2025 median AQI of 45 (Good) with 60.0% Good days
According to the U.S. EPA Air Quality System, the Milwaukee-Waukesha-West Allis, WI CBSA recorded a median AQI of 45 across 365 monitored days in 2025, with 60.0% rated Good and 3 unhealthy or worse. This is an annual metro comparison, not a live advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US metros
- The Milwaukee-Waukesha-West Allis, WI CBSA's 60.0% Good-day share places it cleaner than 25% of US metros in 2025.
- Closest median-AQI peer
- Akron, OH (61.6% Good, median AQI 45) is the closest nationwide median-AQI peer to Milwaukee-Waukesha-West Allis, WI.
- 2020–2025 Good-day shift
- Milwaukee-Waukesha-West Allis, WI's Good-day share moved +9.2 points from 2020 to 2025 (median AQI -3).
- Median AQI
- Median AQI: 45
Aggregated from EPA Air Quality System (2025), 365 monitored days. EPA AQS →
The verdict
Milwaukee-Waukesha-West Allis, WI lands in the lower Good-day tercile (60.0% Good), a thinner clean-air share than most CBSA peers here. On the EPA scale the metro runs good, more polluted than the median US metro, with a median AQI of 45 and 60.0% of 365 monitored days in the Good band.
- 45
- median AQI · Good
- 60.0%
- days rated Good
- 25%
- cleaner than US metros
- 175
- worst single reading
3 days reached Unhealthy or worse across the metro's monitors in 2025.
Annual release change
What changed in the 2025 EPA annual release
- Milwaukee-Waukesha-West Allis, WI metro's Good-day share fell from 66.1% to 62.6% between the 2024 and 2025 EPA annual releases, a change of -3.5 percentage points.
- Milwaukee-Waukesha-West Allis, WI metro's peak single-day AQI rose from 161 to 175 between the 2024 and 2025 EPA annual releases, a change of +14 points.
- Milwaukee-Waukesha-West Allis, WI metro's Unhealthy-category days rose from 2 to 3 between the 2024 and 2025 EPA annual releases, a change of +1 days.
Milwaukee-Waukesha-West Allis, WI lands in the lower Good-day tercile (60.0% Good), a thinner clean-air share than most CBSA peers here. Signature read: 60.0% Good-day share (low tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 45 over 365 measured days in 2025 (Good / Moderate). The monitored-day split lands at 219 Good (60%), 128 Moderate (35%), and 15 Unhealthy-for-Sensitive-Groups (4%). The 90th-percentile AQI finished at 79; the highest single-day reading hit 175 (Unhealthy).
Across 2020–2025, Good-day share shifted +9.2 points and median AQI moved -3 (improving). The annual record contains 3 days at Unhealthy or worse. Metros with comparable AQI profiles include Akron, OH (61.6% good, AQI 45); Ardmore, OK (67.9% good, AQI 45); Asheville, NC (69.9% good, AQI 45).
Air Quality Summary
Median AQI
45
Good
Good Days
60.0%
219 of 365 days
Max AQI
175
Unhealthy
Health Grade
Moderate
90th pct: 79
AQI Day Breakdown (2025)
Distribution of 365 monitored days across EPA AQI categories.
Good
219
60%
Moderate
128
35%
USG
15
4%
Unhealthy
3
1%
Very Unhealthy
0
0%
Hazardous
0
0%
Health Impact Assessment
The Milwaukee-Waukesha-West Allis, WI metro area's air quality is rated Moderate based on 60.0% good air days. There were 3 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 15 days reached "Unhealthy for Sensitive Groups" and peak AQI reached 175. Sensitive groups should monitor real-time conditions at AirNow.gov.
How does the Milwaukee-Waukesha-West Allis, WI metro compare?
How Milwaukee-Waukesha-West Allis, WI compares
5-Year Air Quality Trend
Air quality is improving in the Milwaukee-Waukesha-West Allis, WI metro. Highest Good-day share: 2024 (66.1%, 236 of 357 monitored days).
| Year | Good | Moderate | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|
| 2020 | 192 | 167 | 1 | 48 | 169 |
| 2021 | 149 | 204 | 0 | 53 | 129 |
| 2022 | 182 | 177 | 1 | 51 | 159 |
| 2023 | 159 | 178 | 1 | 53 | 270 |
| 2024 | 236 | 119 | 2 | 45 | 161 |
| 2025 | 219 | 128 | 3 | 45 | 175 |
Metros with a similar median AQI
CBSA peers nationwide whose annual median AQI sits near Milwaukee-Waukesha-West Allis, WI (45).
Akron, OH
Median AQI 45 · 61.6% Good-day share
Ardmore, OK
Median AQI 45 · 67.9% Good-day share
Asheville, NC
Median AQI 45 · 69.9% Good-day share
Cheyenne, WY
Median AQI 45 · 75.1% Good-day share
Clinton, IA
Median AQI 45 · 59.5% Good-day share
Fort Dodge, IA
Median AQI 45 · 59.2% Good-day share
Metros with similar unhealthy-day exposure
A second relationship type: metros whose unhealthy-or-worse day count is closest to Milwaukee-Waukesha-West Allis, WI's 3 (independent of median AQI).
Albuquerque, NM
3 unhealthy-or-worse days · median AQI 61
Detroit-Warren-Dearborn, MI
3 unhealthy-or-worse days · median AQI 54
Fresno, CA
3 unhealthy-or-worse days · median AQI 61
Kansas City, MO-KS
3 unhealthy-or-worse days · median AQI 51
Rochester, MN
3 unhealthy-or-worse days · median AQI 39
St. Cloud, MN
3 unhealthy-or-worse days · median AQI 37
Frequently Asked Questions
How many unhealthy air days does Milwaukee-Waukesha-West Allis, WI have? ▼
What is the air quality in the Milwaukee-Waukesha-West Allis, WI metro area? ▼
Is air quality in Milwaukee-Waukesha-West Allis, WI getting better or worse? ▼
What does AQI 45 mean for health? ▼
How does Milwaukee-Waukesha-West Allis, WI compare to other metro areas? ▼
What is the 90th percentile AQI for Milwaukee-Waukesha-West Allis, WI? ▼
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for Milwaukee-Waukesha-West Allis, WI, 2025. See our methodology for how AQI, median, and coverage figures are computed.
Read our methodology , how this data is sourced, computed, and verified.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by CBSA summary, Milwaukee-Waukesha-West Allis, WI · 2020–2025