FORECAST SUMMARY: Tuesday, June 9, 2026 - Friday, June 12, 2026
Ozone: 8-hour average Ozone concentrations in the Good (AQI Green) to Moderate (AQI Yellow) range are expected; with a few locations possibly reaching the low-end USG (AQI Orange) range.
PM-2.5: 24-hour daily average Fine Particulate concentrations will average between Good and low-Moderate.
FORECAST DISCUSSION:
An active stretch of weather is expected over the next few days, highlighted by building heat and humidity Wednesday and Thursday. Today (Tuesday), a weak low-pressure system will move through the region, producing scattered showers and thunderstorms as it passes. On Wednesday, a warm front will lift north, bringing southwest winds and a surge of hot, humid air. This boundary will support storm development—initially across northern areas earlier in the day, followed by a more organized line of storms later in the afternoon and into the night. A similar setup is expected Thursday. Early-day storms will exit eastern areas, but additional, more organized convection is likely later in the day ahead of an approaching cold front. As the front moves through overnight, winds will shift northwesterly, ushering in cooler and less humid air for Friday.
Fine particulate levels on Tuesday are running in the upper Good to lower Moderate AQI range. Increasing moisture through Thursday may allow concentrations to rise somewhat, but daily averages are still expected to remain within the lower end of the Moderate category. Conditions should improve by Friday, with fine particulate levels returning to the Good range.
On Tuesday, widespread cloud cover and periods of precipitation should keep ozone levels mostly within the Good range. However, some areas may see a few hours of clearing during the afternoon and early evening. If enough sunshine breaks through, ozone could rise quickly. Any increases are expected to remain within the Moderate range, though photochemical models suggest the potential for isolated USG readings in the southwestern portion of Lake Michigan.
A hot and humid southwest flow will prevail Wednesday into Thursday, and periods of thunderstorms are expected across the region. Forecast guidance indicates a break in storms during the daytime hours both days, allowing for at least some clearing. The combination of warm surface and upper‑level temperatures and continued southwest flow would typically support ozone formation. However, dew points are expected to reach the 70s, and moisture levels this high generally limit ozone production. At this time, ozone levels are not expected to exceed the Moderate category. That said, photochemical models still indicate the potential for a few hours of USG readings along portions of the west Michigan lakeshore. If updated model guidance on Wednesday morning suggests a shift toward more widespread USG ozone on Wednesday or Thursday, we will update this forecast accordingly.
EXTENDED FORECAST:
A return to Good air quality is expected late in the week.
Next Forecast update: Friday, June 12, 2026