Pollutant Overview
Ozone (O₃):
8-hour average ozone concentrations are expected to remain Good (Green AQI) to Moderate (Yellow AQI). There is a small chance of Unhealthy for Sensitive Groups (Orange AQI) at select southern Michigan monitors on Tuesday afternoon.
Fine Particulates (PM-2.5):
24-hour average concentrations will be mostly Moderate (Yellow AQI), with improving conditions across southern Michigan as lingering wildfire smoke clears.
Forecast Discussion
Fine particulate concentrations increased across Michigan late Sunday into early Monday due to a north-to-south moving wildfire smoke plume. Hourly PM2.5 levels reached the USG (Orange AQI) range in parts of the southwest, but daily averages remained Moderate across the state.
High pressure will remain in control through Tuesday, bringing plenty of sunshine, comfortable temperatures, and low humidity. Beginning Wednesday, high pressure will shift east as an upper-level ridge (heat dome) builds over the southeastern U.S., bringing hotter, more humid air into Michigan by midweek. A boundary approaching from the north will introduce storm chances beginning Wednesday or Thursday.
For air quality:
PM2.5 levels are expected to improve on Monday, with Good conditions in northern areas and Moderate in the south. Lingering smoke may lead to continued Moderate levels on Tuesday, but higher concentrations are not expected.
Ozone levels will range from Good to Moderate, though surface smoke may enhance ozone formation in some areas. A few southern monitors could briefly reach USG (Orange AQI) levels Tuesday afternoon.
We will continue monitoring conditions and will update the forecast if ozone levels appear likely to rise further as heat and humidity build midweek.
Extended Outlook
Uncertainty remains regarding additional wildfire smoke moving into the region with the expected frontal boundary later this week. Forecasts will be updated accordingly as conditions evolve.