Metro area air quality · 2025

Green Bay, WI

Median AQI 38 (Good). 72.3% of monitored days rated Good across this metro's EPA monitoring network.

38
Median AQI
72.3%
Good-air days
7
Unhealthy days
50%
Cleaner than US metros

Green Bay, WI posted a 2025 median AQI of 38 (Good) with 72.3% Good days

According to the U.S. EPA Air Quality System, the Green Bay, WI CBSA recorded a median AQI of 38 across 365 monitored days in 2025, with 72.3% rated Good and 7 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 Green Bay, WI CBSA's 72.3% Good-day share places it cleaner than 50% of US metros in 2025.
Closest median-AQI peer
Appleton, WI (72.3% Good, median AQI 38) is the closest nationwide median-AQI peer to Green Bay, WI.
2020–2025 Good-day shift
Green Bay, WI's Good-day share moved +2.4 points from 2020 to 2025 (median AQI -1).
Median AQI
Median AQI: 38

Aggregated from EPA Air Quality System (2025), 365 monitored days. EPA AQS →

The verdict

Green Bay, WI's peak reading 175 is in the upper max-AQI tercile among CBSA metros here. On the EPA scale the metro runs good, cleaner than the median US metro, with a median AQI of 38 and 72.3% of 365 monitored days in the Good band.

38
median AQI · Good
72.3%
days rated Good
50%
cleaner than US metros
175
worst single reading

7 days reached Unhealthy or worse across the metro's monitors in 2025.

Annual release change

What changed in the 2025 EPA annual release

2024 → 2025
  • Green Bay, WI metro's Unhealthy-category days rose from 0 to 7 between the 2024 and 2025 EPA annual releases, a change of +7 days.
  • Green Bay, WI metro's peak single-day AQI rose from 105 to 175 between the 2024 and 2025 EPA annual releases, a change of +70 points.
  • Green Bay, WI metro's Good-day share fell from 77.0% to 73.3% between the 2024 and 2025 EPA annual releases, a change of -3.7 percentage points.

Compared against 365 monitored days in 2024 and 360 in 2025. These are arithmetic differences between two stored EPA annual summaries, not a cause claim or a live advisory.

National release changes Two-year CSV

Green Bay, WI's peak reading 175 is in the upper max-AQI tercile among CBSA metros here. Signature read: peak AQI 175 (high tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 38 over 365 measured days in 2025 (Good / Moderate). The monitored-day split lands at 264 Good (72%), 89 Moderate (24%), and 5 Unhealthy-for-Sensitive-Groups (1%). The 90th-percentile AQI finished at 74; the highest single-day reading hit 175 (Unhealthy).

Across 2020–2025, Good-day share shifted +2.4 points and median AQI moved -1 (stable). The annual record contains 7 days at Unhealthy or worse. Metros with comparable AQI profiles include Appleton, WI (72.3% good, AQI 38); Billings, MT (86.3% good, AQI 38); Burlington-South Burlington, VT (87.7% good, AQI 38).

Health effects of air pollution →

Air Quality Summary

Median AQI

38

Good

Good Days

72.3%

264 of 365 days

Max AQI

175

Unhealthy

Health Grade

Moderate

90th pct: 74

AQI Day Breakdown (2025)

Distribution of 365 monitored days across EPA AQI categories.

Good

264

72%

Moderate

89

24%

USG

5

1%

Unhealthy

7

2%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Moderate

The Green Bay, WI metro area's air quality is rated Moderate based on 72.3% good air days. There were 7 unhealthy days in 2025 when outdoor activity should be limited.

Air quality is acceptable most days, but 5 days reached "Unhealthy for Sensitive Groups" and peak AQI reached 175. Sensitive groups should monitor real-time conditions at AirNow.gov.

How does the Green Bay, WI metro compare?

How Green Bay, WI compares

Good-day share better than typical
Green Bay, WI 72.3%
Appleton, WI 72.3%
Typical US metro 70.6%
Median AQI better than typical
Green Bay, WI 38
Appleton, WI 38
Typical US metro 41
Unhealthy days / yr worse than typical
Green Bay, WI 7
Appleton, WI 6
Typical US metro 1

5-Year Air Quality Trend

Air quality is stable in the Green Bay, WI metro. Highest Good-day share: 2024 (77.0%, 281 of 365 monitored days).

Year Good Moderate Unhealthy Median AQI
2020 259 106 0 39
2021 225 135 0 43
2022 256 98 1 42
2023 208 139 6 46
2024 281 84 0 38
2025 264 89 7 38

Metros with a similar median AQI

CBSA peers nationwide whose annual median AQI sits near Green Bay, WI (38).

Appleton, WI

Median AQI 38 · 72.3% Good-day share

38

Billings, MT

Median AQI 38 · 86.3% Good-day share

38

Burlington-South Burlington, VT

Median AQI 38 · 87.7% Good-day share

38

Charlottesville, VA

Median AQI 38 · 81.0% Good-day share

38

Corning, NY

Median AQI 38 · 83.3% Good-day share

38

Dickinson, ND

Median AQI 38 · 82.7% Good-day share

38

Metros with similar unhealthy-day exposure

A second relationship type: metros whose unhealthy-or-worse day count is closest to Green Bay, WI's 7 (independent of median AQI).

Fargo, ND-MN

7 unhealthy-or-worse days · median AQI 37

37

San Diego-Carlsbad, CA

7 unhealthy-or-worse days · median AQI 67

67

Brainerd, MN

8 unhealthy-or-worse days · median AQI 39

39

Chicago-Naperville-Elgin, IL-IN-WI

6 unhealthy-or-worse days · median AQI 56

56

Marquette, MI

6 unhealthy-or-worse days · median AQI 19

19

Minneapolis-St. Paul-Bloomington, MN-WI

6 unhealthy-or-worse days · median AQI 47

47

Frequently Asked Questions

What is the 90th percentile AQI for Green Bay, WI? ▼
The 90th percentile AQI for the Green Bay, WI metro area is 74, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 175 (Unhealthy).
How many unhealthy air days does Green Bay, WI have? ▼
In 2025, the Green Bay, WI metro area recorded 7 unhealthy air days (7 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 175.
What is the air quality in the Green Bay, WI metro area? ▼
The Green Bay, WI metro area has a median Air Quality Index (AQI) of 38, rated "Good." 72.3% of monitored days (264 out of 365) had good air quality in 2025.
Is air quality in Green Bay, WI getting better or worse? ▼
Air quality in the Green Bay, WI metro is stable across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2024 at 77.0% (281 of 365 days). Lowest qualifying Good-day share: 2023 at 58.9% (208 of 353 days).
What does AQI 38 mean for health? ▼
An AQI of 38 is "Good", air quality is satisfactory and poses little or no health risk. This is the best category on the EPA's AQI scale.
How does Green Bay, WI compare to other metro areas? ▼
The Green Bay, WI metro has 72.3% good air days. Similar metros: Appleton, WI (72.3% good), Billings, MT (86.3% good), Burlington-South Burlington, VT (87.7% good).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for Green Bay, 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, Green Bay, WI · 2020–2025