Pollutant Overview
Ozone (O₃):
8-hour average ozone concentrations are expected to range from Good (Green AQI) to Moderate (Yellow AQI) through the forecast period.
Fine Particulates (PM-2.5):
24-hour average concentrations will remain mostly Moderate (Yellow AQI). However, elevated PM2.5 levels are expected across the Upper Peninsula Tuesday afternoon and evening as wildfire smoke drifts into the region.
Forecast Discussion
A weak boundary will continue moving slowly south through Michigan between Tuesday and Wednesday, maintaining hot and humid conditions across the southern half of the state for another day. This boundary will also serve as the focus for scattered thunderstorms, especially across central and northern Michigan.
Relief from the heat and humidity is expected past mid-week as high pressure from Canada moves in, bringing drier air and more comfortable temperatures through the remainder of the week.
For air quality:
PM2.5 concentrations started Tuesday in the upper Good to low Moderate range but are already increasing in the northwest Upper Peninsula due to an incoming plume of wildfire smoke.
This smoke is forecasted to continue moving through the Upper Peninsula during Tuesday and Wednesday, potentially resulting in elevated fine particulate levels.
There is still some uncertainty regarding how far south the smoke will reach; upcoming forecasts will assess if central Michigan may also be impacted later in the week.
For ozone:
Despite sunny skies, storm development is expected on Tuesday. The humid conditions across central and southern Michigan will generally limit ozone formation.
While a few isolated sites may briefly reach low-end USG levels, most areas are expected to remain within the Moderate range.
Ozone levels are expected to improve by Wednesday as northerly winds behind the front bring in cleaner air.
Extended Outlook
The extended forecast looks favorable with comfortable temperatures and sunny skies as high pressure settles over the region. However, we will continue to monitor smoke trends to determine if any lingering impacts on air quality will persist through the end of the week.
Next Forecast Update: Wednesday, July 30, 2025