FORECAST SUMMARY: Monday September 8th, 2025, through Friday September 12th, 2025
Ozone:
Ozone concentrations are expected to be in the Good (Green AQI) to Moderate (Yellow AQI) range.
PM-2.5:
PM-2.5 concentrations are expected to be in the Good (Green AQI) to Moderate (Yellow AQI) range.
FORECAST DISCUSSION:
A Pure Michigan Fall weekend will give way to a taste of summer this week with the 80s returning to the majority of the state.
We start off this week with the mid-60s expected across the entire state with light south-southwesterly winds. Come Tuesday, however, a warm front will start to make its way into the Great Lakes, which will increase surface temperatures further, but will bring spotty rain showers to northern areas, mainly the upper peninsula. Temperatures slowly increase throughout this week, with the upper peninsula falling slightly behind due to the chance of additional scattered rain on Wednesday. To break up and minimize rain chances, a High-pressure system drifts in from the north during the latter half of this week which will further provide increasing temperatures as winds shift to predominantly southerly flow, bringing in warmer air. To cap off the week, Friday looks to be the warmest day of the work week with most areas across the state well into the 80s, along with ample sunlight.
For air quality, PM-2.5 and associated wildfire smoke does not look to be an issue this week as most of the smoke is staying out west and north in Canada. Additionally, the southerly flow this week will help to keep wildfire smoke from entering the Great Lakes State. For Ozone this week, temperatures returning to the 80s, southerly flow, and ample sunlight will allow for the photochemical reaction that produces Ozone to kick off development, more so in the latter half of this week. However, the southwesterly flow, as of now and the predominant driver for Ozone development in southwest Michigan, will be rather sparse and sporadic throughout this week, so widespread hourly Unhealthy for Sensitive Groups concentrations are not expected at this time. Moderate to potentially high-Moderate concentrations can be expected, though. With mid-September approaching, the sun angle and intensity of the sun is decreasing by the day, so this will help lessen the development of Ozone as we start to approach the end of Ozone season. If any changes occur to Ozone guidance later this week, an updated forecast will be sent out.
EXTENDED FORECAST:
The weather pattern this week seems to persist as plentiful sunlight, and 80-degree temperatures carry us into the weekend. Air quality will remain in the Good to Moderate range.
Next Forecast update: Friday September 12th, 2025