Check a local allergy forecast for pollen levels. Air quality and pollen measure different things.
Green Bay air quality in 2024
Days with good air
79%
290 of 366 days
Median AQI
37
Good
Unhealthy-for-sensitive days or worse
0
Main pollutant
PM2.5
209 days
Worst reading
AQI 87
Moderate
Good: 290 days
Moderate: 76 days
Air quality by month
Average daily AQI for each month, 2022–2024. March is usually the cleanest month and June the worst.
42Jan63% good
39Feb66% good
33Mar84% good
43Apr83% good
48May74% good
59Jun61% good
46Jul58% good
43Aug66% good
41Sep70% good
38Oct77% good
34Nov78% good
40Dec65% good
Ten-year trend
20151 daysmedian 42
20163 daysmedian 36
20170 daysmedian 38
20181 daysmedian 42
20190 daysmedian 40
20201 daysmedian 39
20213 daysmedian 43
20222 daysmedian 40
202313 daysmedian 44
20240 daysmedian 37
Bars show days each year at “unhealthy for sensitive groups” (AQI above 100) or worse.
Worst air days, 2022–2024
179June 28, 2023 · Unhealthy · fine particles (PM2.5)
177June 27, 2023 · Unhealthy · fine particles (PM2.5)
174June 29, 2023 · Unhealthy · fine particles (PM2.5)
165June 26, 2023 · Unhealthy · fine particles (PM2.5)
163June 4, 2023 · Unhealthy · fine particles (PM2.5)
Reading the AQI
Ozone forms on hot, sunny afternoons, so it peaks in summer; plan runs and outdoor play for the morning on high-ozone days. Fine particles (PM2.5) come from wildfire smoke, traffic and wood burning and can spike in any season. Above 100, people with asthma, heart or lung conditions, older adults and children should limit long or heavy exertion outdoors.
In 2024, 79% of days had good air (AQI 50 or below) at Brown County monitors, 21% were moderate and 0 days reached unhealthy for sensitive groups or worse. The median AQI was 37.
When is air quality worst in Green Bay?
From 2022 to 2024, June had the highest average AQI (59) and March the lowest (33).
What is the main air pollutant in Green Bay?
fine particles (PM2.5) was the main pollutant on 209 of 366 days in 2024.
Is Green Bay’s air getting better or worse?
The median AQI was 42 in 2015 and 37 in 2024; days at unhealthy for sensitive groups or worse went from 1 to 0.