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 (Orange AQI), particularly in parts of southern Lower Michigan.
Fine Particulates (PM-2.5):
24-hour average concentrations will remain mostly Moderate (Yellow AQI) statewide, with potential increases due to wildfire smoke later in the forecast period.
Forecast Discussion
A frontal boundary is progressing south through Michigan, bringing a shift in weather and air quality conditions:
On Wednesday, the front will bring precipitation to the Upper Peninsula and parts of Northern Lower Michigan, while sunny skies continue further south.
Temperatures will rise into the 80s on Wednesday and climb into the 90s on Thursday across much of the Lower Peninsula.
Heat indices may approach 100°F in the south on Thursday. With the increasing humidity, outdoor conditions will become uncomfortable, and heat safety precautions are advised.
For air quality:
PM2.5 levels have remained in the upper Good to low Moderate range, and similar levels are expected through Wednesday.
Smoke models suggest a plume of wildfire smoke may move into the Upper Peninsula Thursday afternoon, gradually pushing into southern Michigan by late Thursday into Friday. If current trends continue, PM2.5 may approach USG levels in affected regions. This will be closely monitored for potential air quality alerts.
Ozone levels are forecast to remain Moderate, with Good conditions in the north. Sunshine and warming temperatures may allow for localized increases on Wednesday, but increased humidity and cloud cover Thursday will likely limit ozone formation. A small chance exists for isolated USG levels, though not enough to warrant a pollution alert at this time.
Extended Outlook
There is continued uncertainty in the extended forecast regarding:
The timing and intensity of precipitation
The trajectory of additional smoke plumes
The influence of lingering heat and humidity on pollutant levels
Further forecast updates will provide additional detail as conditions evolve through the end of the week.