FORECAST SUMMARY: Monday, August 31, 2026 – Friday, September 4, 2026
Ozone: 8-hour average concentrations in the Good (Green AQI) to Moderate (Yellow AQI) range are expected; a small chance for Unhealthy for Sensitive Groups (USG, Orange AQI) exists in the west/southwest Tuesday and Wednesday.
PM-2.5: Concentrations will range from mostly Moderate.
FORECAST DISCUSSION:
Warm, humid weather will continue through mid‑week as a frontal system moves across the region. Periods of showers and thunderstorms are likely, but the timing of each round is uncertain. Any afternoon or early evening sunshine that breaks through the cloud cover could allow ozone levels to rise quickly. Some increases in fine particles are also possible throughout the period. A cold front is expected to move through Wednesday into Thursday. As cooler, cleaner air arrives from the northwest, air quality should improve.
The current weather pattern makes the ozone forecast a bit challenging. Michigan will remain under a warm airmass and a southerly wind flow through Wednesday, conditions that typically support ozone formation. However, frequent chances for showers, clouds, higher humidity, and the shorter daylight period this time of year should help limit how much ozone can develop. Forecast models indicate the potential for rising ozone levels in western and southwestern parts of the state on Tuesday and Wednesday. This could occur if clouds break apart and sunshine returns during the afternoon or early evening. As a result, Moderate ozone levels are being forecast in those areas. While not likely, a brief period of low‑end Unhealthy for Sensitive Groups (USG) is possible if conditions align. Elsewhere across Michigan, ozone is expected to stay in the Good to low‑Moderate range.
Moderate fine particulate readings have been steady across central and southern parts of the state. Increased humidity and persistent southerly winds will likely keep concentrations in the upper Good to mid‑Moderate range through mid‑week. As winds shift to the northwest Thursday into Friday, cleaner air is expected to move in, helping levels improve back toward the Good range.
Recent evaluations of wildfire activity in Canada show a noticeable decrease in both the number and intensity of fires from early August to the end of the month. This is encouraging news, but we continue to monitor conditions closely—both in Canada and across the U.S. Smoke model guidance indicates light plumes drifting over the region at times this week. While impacts appear minimal, we will keep track of any changes that could affect air quality.
EXTENDED FORECAST:
Air Quality is expected to remain mostly Good in the extended period.
Next Forecast update: Friday, September 4, 2026