Pollutant Overview
Ozone (O₃):
8-hour average ozone concentrations are expected to range from Good (Green AQI) to Moderate (Yellow AQI). A small chance exists for Unhealthy for Sensitive Groups (USG, Orange AQI) levels in southern Michigan.
Fine Particulates (PM-2.5):
24-hour average concentrations will be mostly Moderate (Yellow AQI) statewide. USG levels are possible in the Upper Peninsula on Tuesday due to wildfire smoke.
Forecast Discussion
A weak frontal boundary will gradually move through Michigan between late Monday and Wednesday, bringing opportunities for scattered thunderstorms. Ahead of this front, hot and muggy conditions will continue across much of the state.
Relief from the heat is expected past mid-week as high pressure from Canada sinks southward, ushering in cooler and less humid air along with more comfortable temperatures for the latter half of the week.
For air quality:
PM2.5 levels on Monday morning were ranging between upper Good and low Moderate, and similar levels are expected into Tuesday. However, the Upper Peninsula may experience increasing PM2.5 concentrations on Tuesday as wildfire smoke enters the region. Forecast updates will evaluate if these levels will rise enough to warrant an advisory.
With high pressure expected to settle in later this week, there is potential for smoke to linger and become trapped near the surface, which we will continue to monitor.
For ozone:
A fair amount of sunshine is expected on Monday and Tuesday, with hot and humid conditions in place, especially across central and southern Michigan.
While humidity generally limits ozone formation, isolated areas could still reach low-end USG levels.
By Wednesday, air quality conditions should improve as northerly winds push through behind the front.
Extended Outlook
The extended forecast calls for comfortable temperatures and plentiful sunshine through the end of the week. However, smoke presence will continue to be evaluated to determine any lingering impact on air quality.
Next Forecast Update: Tuesday, July 29, 2025