Department meteorologists use monitoring data and weather forecast models to predict Wisconsin's future ozone (O₃) and fine particulate matter (PM_2.5) air quality using the Air Quality Index (AQI) [exit DNR]. This forecast is updated two-to-three times weekly throughout the year, and when warranted, an Air Quality Advisory is issued. Below is the latest air quality forecast for Wisconsin.

Friday, September 19 - Thursday, September 25, 2025

Ozone

Good (Green) to Unhealthy for Sensitive Groups (Orange) AQI levels.

Particle pollution (PM_2.5)

Good (Green) to Moderate (Yellow) AQI levels.

Short-Term Forecast Maps:

The black dots represent the approximate location of Wisconsin's air quality monitors. Read the forecast summaries below for further geographic information.

Short-Term Forecast (Days 1-3)

Updated Friday, September 19 - 11:10 AM

A stubborn area of low pressure will continue to impact the state today and through the weekend as an upper level low slowly drifts from the northern Plains into the Great Lakes. Precipitation chances will remain mostly confined to the western half of the state through much of Friday, before increasing across eastern areas later Friday. Statewide precipitation chances will then be in place on Saturday before drier conditions reach western areas on Sunday, when better chances for precipitation become concentrated over the eastern half of the state. We will likely see ozone concentrations become elevated once again across southeastern portions of the state today, with Moderate (Yellow) AQI ozone forecast there. We cannot rule out Unhealthy for Sensitive Groups (Orange) AQI ozone, but any cloud cover or precipitation reaching this area in the early afternoon should limit ozone production. Although mostly Good (Green) AQI PM2.5 is forecast for today, the best chances for Moderate (Yellow) AQI PM2.5 will reside across more southern and western areas. As the low pressure area moves through the state over the weekend, we should trend more towards statewide Good (Green) AQI. However, some areas of Moderate (Yellow) AQI ozone or PM2.5 will be possible each day.

Extended Outlook (Days 4-7)

Long-range models appear to be in agreeance that Monday will be another day with southerly flow and precipitation chances for southern areas, but then northerly flow returns statewide Tuesday and continues through the extended period. As such, chances for Moderate AQI look to stick around southern areas on Monday before we trend towards statewide Good AQI for the remainder of the extended period.

Air Quality Index (AQI) ranges

For more information about AQI ranges and colors, see the U.S. EPA's Air Quality Index (AQI) Basics [exit DNR].