FORECAST SUMMARY: Saturday, June 21, 2025 - Sunday, June 22, 2025
Ozone: 8-hour ozone concentrations are expected to range between Good (Green AQI) and Moderate (Yellow AQI), with USG (Orange, AQI) possible along the west Michigan lakeshore.
PM-2.5: 24-hour daily average Fine Particulate concentrations will range between upper Good and Moderate.
Air Quality Advisory for Saturday, June 21, and Sunday, June 22, 2025
The Michigan Department of Environment, Great Lakes, and Energy (EGLE) has declared an Air Quality Advisory for June 21 and June 22, 2025, for elevated levels of ozone in western counties of Michigan. Pollutants within those areas are expected to be in the Unhealthy for Sensitive Groups (USG, Orange AQI) range.
The Air Quality Advisory for Saturday is in effect for the following Michigan counties:
Allegan, Berrien, Cass, Kent, Muskegon, Ottawa, and Van Buren
The Air Quality Advisory for Sunday is in effect for the following Michigan counties:
Allegan, Antrim, Benzie, Berrien, Cass, Charlevoix, Emmet, Grand Traverse, Kent, Leelanau, Manistee, Mason, Muskegon, Oceana, Ottawa, and Van Buren
FORECAST DISCUSSION:
Hot temperatures and humidity continue to be the main forecast points for this weekend into early next week. Temperatures in the 90s, along with increased humidity, will make it “feel” like 100+ degrees in parts of the state. Those with outside plans should exercise caution. Storms and clouds in northern and eastern portions of the state on Saturday should keep ozone from increasing significantly in those locations. However, with ample sunshine expected in the southwest, along with a warm surface and upper-level flow, the environment will be favorable for ozone development. Because of this threat, we have issued an Air Quality Advisory for Saturday, which includes Muskegon and areas south to the state line.
The heat and humidity continue to build Sunday, and more in the way of sunshine is expected across the state. Ozone-conducive conditions will increase in the northern lakeshore areas Sunday; therefore, we have expanded the advisory for ozone north, along the west Michigan lakeshore. Across the rest of the state, ample sunshine is expected, along with hot temperatures; however, we anticipate the strong winds and high humidity levels to keep ozone from reaching higher than Moderate. Without an airmass change expected in the short-term, the threat of increased ozone will continue. This forecast will be updated Sunday to determine the need to continue or expand the current air quality advisory.
Ozone will be the dominant pollutant through early next week. We anticipate increases in PM2.5 concentrations during this period, but we do not expect daily averages to exceed the low to middle Moderate range.
EXTENDED FORECAST:
Extended models show the heat and humidity lingering into next week. We will be updating the forecast throughout the weekend do determine if air quality advisories are needed later in the forecast period.
Next Forecast update: Sunday, June 22, 2025