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.

Thursday, April 25 - Wednesday, May 1, 2024

Ozone

Good to Moderate levels.

Particle pollution (PM_2.5)

Good to Moderate 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)

Clear skies associated with high pressure conditions allowed for quite the near-surface inversion over Wisconsin this morning, with many locations seeing temperatures near freezing. Plentiful sunshine today with light winds from the southeast will allow temperatures to rebound into the mid-to-upper 50s. Despite the relatively cool temperatures, the weak wind speeds with ample sunlight will increase the chances for ozone production. The southeasterly flow, albeit light, may begin to bring some trace smoke into the region from burning in the southeastern U.S. Good to Low-Moderate AQI for both ozone and PM2.5 is expected today. As a developing surface low approaches from the west tomorrow, wind speeds over Wisconsin will increase. Clear skies overnight are expected to give way to cloudier conditions by the afternoon hours, with temperatures reaching the low 60s. Precipitation is expected to track west to east across the state, beginning in the afternoon and continuing through the overnight hours. Low-Moderate AQI for ozone and PM2.5 will be possible for counties to the northeast, with other locations more likely to remain in Good AQI. As the surface low passes through the northwestern part of the state on Saturday, robust southerly winds will allow temperatures to warm into the 70s, with a significant increase in atmospheric moisture. A moderate westerly component to the winds will likely inhibit the ability of any lake breeze to push on shore in the afternoon. However, elevated ozone will still be possible for lakeshore counties if a lake breeze can develop. By early evening, a cold front will begin to drop in from the north, clearing out the northern two thirds of the state overnight. Overall, Good AQI for PM2.5 is expected. Good to Moderate AQI for ozone is forecast, with lakeshore counties having the highest chances for Moderate AQI.

Extended Outlook (Days 4-7)

On Sunday, long-range meteorological guidance suggests the development of another surface low pressure system in the Central Plains, shifting winds over Wisconsin to easterly. The cold front from Saturday may stall somewhere over southern Wisconsin on Sunday morning before slowly pushing back north as a warm front Sunday afternoon and evening. Good AQI is expected for locations north of this boundary, with Moderate AQI for both ozone and PM2.5 possible for locations in the warmer air mass on the southern side of the front. As the surface low passes through the region, conditions look similar to Saturday, with Moderate AQI possible along the lakeshore and Good AQI likely elsewhere. Impacts from yet another low pressure system are anticipated on Tuesday, with high pressure forecast to take hold on Wednesday. Though active meteorological patters typically favor cleaner conditions, the warmer temperatures and recurring southerly flow will favor ozone production and the transport of residual smoke from continued burning in the southeastern U.S. For now, Good to Moderate AQI is forecast for the remainder of the extended outlook.

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].