8/25/2025 Air Quality Forecast

FORECAST SUMMARY: Monday, August 25, 2025, through Friday, August 29, 2025

OZONE: 8-hour average Ozone concentrations are expected to be mostly Good (AQI Green).

PM-2.5: 24-hour average Fine Particulate concentrations are also expected to be mostly Good (AQI Green).

FORECAST DISCUSSION

It has been a while since I have been able to write a forecast predicting Good AQI’s for a whole work week.  That is quite a treat from the past three months where we were on the edge of our seats watching Canadian wildfire smoke drift our direction. 

It has been a summer for poor Air Quality thanks to unprecedented Canadian wildfires.  While the number of 2025 Canadian wildfires have been roughly average, the size of the area burned has been twice the size of an average summer.  Many of those fires are further east than the typical Canadian fires we normally see in the more western provinces.  The closer the fires, the more likely thick smoke will reach the Midwest. 

The good news is that recent rains, through much of Canada, have reduced the area susceptible to new fire.  And it has helped knock down much of the smoke from existing fires which should be starting to burn out with the approach of cooler weather.  A check of the AirNow.gov maps shows the vast majority of the United States and Canada currently under Good AQI. 

Weatherwise, this week will continue to be a preview of Fall conditions.  A cooling trend will continue as a low-pressure trough slides eastward that will likely kick off a few light lake effect showers, mostly across northern lower and closer the Lake Michigan shoreline.  A high-pressure cell will work its way through the Ohio Valley to central Appalachia, Tuesday night and Wednesday, resulting in dryer weather for the second half of the week.  Even as westerly winds draw in a slightly warmer air, I am not expecting to see the thermometer break the 80-degree mark until perhaps Labor Day.  Nights will be noticeably chillier with temperatures dropping into the high 40’s on some nights.  So, ozone development is not expected to be an issue, either. 

EXTENDED FORECAST:

 Air Quality is expected to remain mostly Good for the holiday weekend. 

8/22/2025 Air Quality Forecast

FORECAST SUMMARY: Friday, August 22, 2025 - Monday, August 25, 2025

Ozone: 8-hour ozone concentrations are expected to range mostly Good (Green AQI) with a few Moderate (Yellow AQI) concentrations possible south on Friday and Saturday.

PM-2.5: 24-hour daily average Fine Particulate concentrations will average Good with a few low Moderates Friday and Saturday.

FORECAST DISCUSSION:

This weekend Michigan will experience fall-like conditions for the first time this season. The cool down happens as cold air filters in behind a cold front tracking northwest to southeast today, Friday, through Saturday. Precipitation also moves in, starting in the upper peninsula Friday and continuing into the lower peninsula Saturday. High temperatures on Friday will range from the 70s in the north to the 80s in the south. By Sunday, high temperatures will struggle to reach the 60s in the upper peninsula and the low to mid 70s in the south. Low temperatures will fall into the 40s later in the forecast period. Temperatures on Sunday will be cold enough for lake effect precipitation to develop due to the cold northwesterly flow over the warmer lake water.

For air quality, mostly Good levels of both ozone and fine particulate can be expected this forecast period. The only chance for low Moderate concentrations for either pollutant would be Friday or Saturday in southern locations. Earlier this summer northwest winds have brought increased PM2.5 concentrations due to the Canadian wildfires. We did evaluate current smoke conditions, and while the Canadian fires persist, the fire intensities are currently low, and they are not generating much smoke. Because of this, we do not expect an increase in PM2.5 concentrations this forecast period.

EXTENDED FORECAST:

Cool Canadian air lingers into the new workweek, and we expect Good air quality levels during this period.

Next Forecast update: Monday, August 25, 2025

8/18/2025 Air Quality Forecast

FORECAST SUMMARY: Monday, August 18, 2025 - Friday, August 22, 2025

Ozone: 8-hour ozone concentrations are expected to range mostly Good (Green AQI) with only a few Moderate (Yellow AQI) concentrations possible south.

PM-2.5: 24-hour daily average Fine Particulate concentrations will average upper Good to middle Moderate.

 FORECAST DISCUSSION:

Two weather systems bring showers and storms into the forecast this week. The first one moves west to east through the region Monday into Tuesday, with the second one moving in Friday into early Saturday. Conditions dry out in the wake of each system as high pressure builds in; less humidity and more comfortable temperatures can be expected as well. High temperatures during the workweek will range from around 70 in the north to around 80 in the south. By the weekend, high temperatures fall to the 60s in the north and 70s in the south.

We expect ozone concentrations this week to range mostly Good thanks to the cooler surface and upper-level temperatures, along with clouds associated with the systems moving through. Northwesterly winds this summer have brought down smoke from Canadian wildfires; however, fire intensities and fire hotspots have improved over the last week or two. These improvements have helped decrease smoke production and therefore have reduced the threat of smoke moving into our region. Based on current smoke and forecast models, we do not anticipate PM2.5 to reach higher than the middle Moderate range. We will continue to evaluate updated smoke and forecast models as the week progresses, and this forecast will be updated if we expect PM2.5 concentrations to reach higher than what is currently forecast.

EXTENDED FORECAST:

Cool Canadian air sinks into the region behind the Friday/Saturday front. At this time, smoke moving in behind the boundary is not a concern; however, we will be tracking smoke models as the week progresses. Air quality late in the forecast period should be no higher than Moderate.

Next Forecast update: Friday, August 22, 2025

8/15/2025 Air Quality Forecast

FORECAST SUMMARY: Friday August 15, 2025, through Monday August 18, 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 Moderate (Yellow AQI) range.

FORECAST DISCUSSION:

We incredulously enter mid-August this upcoming weekend with summer-like temperatures continuing in the lower peninsula and cooler temperatures in the upper peninsula. Surface high temperatures are expected to be in the mid-to-upper 80s for the lower peninsula with high dewpoints expected throughout southern Michigan. For the upper peninsula, a weak pressure system and frontal boundary will linger in the Northwoods this weekend to produce northerly flow, which in turn, will keep northern areas cooler and slightly drier.

With the majority of the southern Great Lakes dealing with high dewpoints and humidity, pop up showers should be expected throughout this weekend along with the possibility of a few lines of rain and potential storms. As of now, the areas with the greatest chance of precipitation will be western and northern areas. This weekend will not be a complete wash out, as some models are showing rain dissipating earlier than others, but some areas across Michigan will see precipitation.

For air quality, region-wide Moderate PM-2.5 concentrations are being reported currently with those concentrations expected to persist throughout the weekend. Relatively light winds will lessen the dispersion capability of these concentrations which is why they are expected to linger. For Ozone, a few of the ingredients for Ozone development will be present this weekend, but cloudy conditions and high dewpoints will help keep Ozone at bay. We have seen historically when dewpoints reach the upper-60s and into the low-70s, the Ozone chemical reaction does not react well within the atmosphere. One thought is that the air is too heavy and moist for the precursors to react with residual Oxygen atoms. Another is that there is too much moisture in the air so the UV radiation coming in is being scattered and refracted by the water droplets in the air, so the reaction to produce Ozone does not occur effectively. Due to these conditions in place this weekend, mid to potentially high Moderate Ozone concentrations are expected.

EXTENDED FORECAST:

The airmass this weekend continues into late Sunday with a cooldown expected early to mid-next week. Air quality is expected to range between the Good and Moderate range.

Next Forecast update: Monday August 18, 2025

8/12/2025 Air Quality Forecast

FORECAST SUMMARY: Tuesday August 12, 2025, through Friday August 15, 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 Moderate (yellow AQI) range with potential hourly concentrations in the Unhealthy for Sensitive Groups (Orange AQI) range.

Air Quality Advisory for the Upper Peninsula until noon on Tuesday, August 12th

 The Michigan Department of Environment, Great Lakes, and Energy (EGLE) has issued an Air Quality Advisory for elevated levels of fine particulate (PM2.5) across the Upper Peninsula of Michigan. Pollutants within those areas are expected to be in the Unhealthy for Sensitive Groups (USG, Orange AQI) range.

The Air Quality Advisory includes the following counties:

Alger, Baraga, Chippewa, Delta, Dickinson, Gogebic, Houghton, Iron, Keweenaw, Luce, Mackinac, Marquette, Menominee, Ontonagon, Schoolcraft

FORECAST DISCUSSION:

Currently, there is an Air Quality Advisory in place for the Upper Peninsula which will be expiring at noon today, Tuesday August 12th. Most recent smoke models are showing the plume becoming less and less intense as we get into Tuesday afternoon and evening. Now, there may be a possibility of hourly USG (Orange AQI) concentrations, but overall concentrations are expected to remain in the mid-to-high Moderate (Yellow AQI) range.

Later this evening and into overnight, a cold front will cross over the Great Lake region, providing a good chance at rain showers across Michigan. This cold front will also shift winds to a more northerly direction, initially northwesterly, before turning to a more northeasterly direction on Thursday. With the shift in winds, our eyes will be watching for any more smoke intrusions later this week, but as of now, smoke, and associated PM-2.5 concentrations look to remain in the Moderate (Yellow AQI) range through the remainder of this week.

For Ozone, after today, as mentioned above, winds shift to an unfavorable direction for Ozone development for the remainder of the work week, so Ozone does not pose a real threat for the next couple of days. Today may see an increase into the high-Moderate (Yellow AQI) range, but with chances of rain and northerly winds this week, Ozone will remain in the Good to Moderate range.

Surface temperature-wise, we still hang around the 80s for the majority of Michigan with ample sunlight with the exception of later Tuesday and early Wednesday. A weaker cold front looks to impact us on Thursday, but a slight change of wind direction looks to be the only impact, with little to no chance of rain expected. Air and dewpoint temperatures look to climb as we approach the end of this week with the weekend ahead looking to be similar to last weekend: hot and muggy.

EXTENDED FORECAST:

A similar set up compared to last weekend is expected to occur this upcoming weekend with heat and humidity returning. Air quality is expected to be in the Good (Green AQI) to Moderate (Yellow AQI) range.

Next Forecast update: Friday August 15, 2025

8/11/2025 Air Quality Forecast

FORECAST SUMMARY: Monday August 11, 2025, through Tuesday August 12, 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 Unhealthy for Sensitive Groups (Orange AQI) range.

 Air Quality Advisory for the Upper Peninsula on Monday, August 11th until noon on Tuesday, August 12th

 The Michigan Department of Environment, Great Lakes, and Energy (EGLE) has issued an Air Quality Advisory for elevated levels of fine particulate (PM2.5) across the Upper Peninsula of Michigan. Pollutants within those areas are expected to be in the Unhealthy for Sensitive Groups (USG, Orange AQI) range.

 The Air Quality Advisory includes the following counties:

 Alger, Baraga, Chippewa, Delta, Dickinson, Gogebic, Houghton, Iron, Keweenaw, Luce, Mackinac, Marquette, Menominee, Ontonagon, Schoolcraft

 FORECAST DISCUSSION:

We start off this new work week with surface temperatures expected to range from the upper-70s to upper-80s with relatively high dewpoint temperatures as well. A predominantly southwest wind will keep temperatures high Monday afternoon and into Tuesday with rain chances increasing we go into Monday afternoon and evening. Rain chances remain on Tuesday as well, with the capability of storms producing.

There is currently an Air Quality Advisory in place for the Upper Peninsula today, through noon on Tuesday. Wildfire smoke from Canadian fires is expected to move through the upper Great Lakes today and tomorrow, Tuesday. After this initial plume moves through, a potential additional plume may cross over the same areas into Wednesday due to a cold front moving through the region. If there needs to be an extension of the Advisory, it will be made on Tuesday morning when this forecast is updated.

Ozone development will be watched this afternoon and into Tuesday as favorable conditions exist for Ozone to produce over west and southwest Michigan. However, high dewpoint temperatures and the potential of rain showers are currently looking to keep Ozone development at bay. Mid-to-high Moderate concentrations are expected with the possibility of hourly Unhealthy for Sensitive Groups concentrations in southwest Michigan. As of now, the 8-hour Ozone average is expected to remain in the Moderate range.

EXTENDED FORECAST:

A slight cool down is expected mid-to-late week after a cold front moves through and drops surface high temperatures into the low-80s. This is short-lived as hot temperatures return for the weekend ahead, along with high dewpoints. Ozone and PM-2.5 concentrations will be monitored throughout the week.

Next Forecast update: Tuesday August 12, 2025

8/10/2025 Air Quality Forecast

FORECAST SUMMARY: Sunday, August 10, 2025 - Monday, August 11, 2025

Ozone: 8-hour ozone concentrations are expected to range between Good (Green AQI) and Moderate (Yellow AQI).

PM-2.5: 24-hour daily average Fine Particulate concentrations will average mostly Moderate with Unhealthy for Sensitive Groups (USG, Orange AQI) range possible in the Upper Peninsula on Monday.

 Air Quality Advisory for the Upper Peninsula on Monday, August 11th until noon on Tuesday, August 12th

 The Michigan Department of Environment, Great Lakes, and Energy (EGLE) has issued an Air Quality Advisory for elevated levels of fine particulate (PM2.5) across the Upper Peninsula of Michigan. Pollutants within those areas are expected to be in the Unhealthy for Sensitive Groups (USG, Orange AQI) range.

 The Air Quality Advisory includes the following counties:

 Alger, Baraga, Chippewa, Delta, Dickinson, Gogebic, Houghton, Iron, Keweenaw, Luce, Mackinac, Marquette, Menominee, Ontonagon, Schoolcraft

FORECAST DISCUSSION:

This forecast update is warranted due to wildfire smoke entering the Upper Peninsula of Michigan starting Monday morning. This is happening as a low-pressure area to our north across Ontario moves northeast, bringing a cold front towards the Great Lakes region. Hourly levels of PM2.5 on Sunday morning were in the USG to Unhealthy range across the Dakotas as northerly winds behind the boundary pulled smoke plumes south.

 As the front tracks east Sunday into Monday, the smoke plume moves east as well. Wildfire smoke is expected to enter the western Upper Peninsula early Monday, pushing east through the day. At this point it looks like smoke should stay north and west of the Lower Peninsula; however, current weather and smoke models will be evaluated Monday morning to determine if the air quality advisory will need to be expanded into other parts of the state. Levels of PM2.5 in the USG range are likely Monday across the Upper Peninsula with some locations reaching the Unhealthy (Red, AQI) range for a few hours. Levels across the rest of the state will range mostly Moderate.

 Muggy conditions and clouds associated with storm chances will keep ozone from reaching higher than Moderate Sunday or Monday.

 EXTENDED FORECAST:

Smoke could linger on Tuesday along with chances for precipitation. High pressure then moves in past mid-week.

Next Forecast update: Monday, August 11, 2025

8/7/2025 Air Quality Forecast

Air Quality Forecast: Thursday, August 7 – Friday, August 8, 2025

Ozone:
8-hour average ozone concentrations are expected to range from Good (Green AQI) to High Moderate (Yellow AQI), with the potential for scattered Unhealthy for Sensitive Groups (USG, Orange AQI).

PM-2.5:
Fine particulate (PM-2.5) concentrations are expected to remain mostly Moderate (Yellow AQI).

Summary:
Air quality continues to improve compared to the previous week. Most areas reported Moderate AQI on Wednesday, with the only USG readings occurring in the Upper Peninsula. Easterly and southerly winds are helping to keep wildfire smoke and ozone precursors out of the region, though hazy conditions may linger due to high humidity and residual particulates.

Ozone levels are expected to remain mostly moderate, though some scattered USG levels are possible Thursday. Cloud cover and scattered showers on Friday should limit additional ozone buildup.

While the worst of the smoke has moved on, wildfires in Canada continue. Forecasts suggest continued southerly winds, which should help keep most smoke north of the state in the coming days.

Next forecast update expected Friday morning.

8/6/2025 Air Quality Forecast

OZONE: 8-hour average Ozone concentrations are expected to range between Good (AQI Green) and High Moderate (AQI Yellow).

PM-2.5: 24-hour average Fine Particulate concentrations are expected to be mostly High Moderate (AQI Yellow) with scattered Unhealthy for Sensitive Groups (USG) (AQI Orange), especially in the Northern Lower Peninsula and Upper Peninsula.

FORECAST DISCUSSION

As I checked the current Wednesday morning monitor readings I was relieved to see more Moderate readings than USG or Unhealthy.  It has been over a week since that has occurred, and those monitors are continuing to trend downward!  Yes, when you looked outside, this morning, you were still seeing hazy conditions.  Although trending downward, the current High Moderate concentrations will not give us the bright blue skies we have been seeking.  Fortunately, much of this morning’s haze comes from high humidity and good, old fashion fog.  That fog should burn off and some haze will persist, but it should not be as bad as what we have been experiencing for well over a week.  As a result, all current Air Quality Advisories for smoke will be discontinued beginning Thursday, although High Moderate conditions are likely to persist.

The air quality smoke models indicate that this improvement trend should continue.  The long-range smoke models have a bit of elevated smoke touching the western U.P. during Monday but that remains to be seen. 

The southerly winds we are expecting beginning Thursday should keep the Canadian smoke at bay, but it will bring heat and humidity for the foreseeable future.  As mentioned in previous forecasts, elevated ozone could be our next challenge.  A review of yesterday’s Midwest monitor summary showed some elevated ozone around Chicago and Milwaukee.  The easterly winds that are pushing the smoke out of Michigan are also keeping most of the ozone producing chemicals on their side of the lake.  Since it is hard to predict if enough leftover smoke residue is around Michigan to produce ozone, plus southerly winds bringing heat, humidity, and potentially dirtier air from down south, we will update this forecast Thursday morning.

EXTENDED FORECAST:

Air Quality remains in question while some leftover smoke residue remains in the air and ozone levels may increase.

08/04/2025 Forecast Update

Monday, August 4, 2025 – Tuesday, August 5, 2025

Ozone

Ozone concentrations will range from Good (Green AQI) to Moderate (Yellow AQI).

PM-2.5

Fine particulate levels will be mostly Unhealthy for Sensitive Groups (USG, Orange AQI), with brief periods of Unhealthy (Red AQI) possible.

Forecast Discussion

Wildfire smoke from Canada and a persistent high-pressure system continue to trap haze across Michigan. Most monitors are reporting USG (Orange AQI), with some hitting Unhealthy (Red AQI) levels.

Conditions are expected to stay hazy through Tuesday. Improvements may come mid-week as the high-pressure system moves out, but forecasts will be updated as needed.

Ozone could rise later this week, especially with warmer temperatures and lingering pollutants.

Extended Forecast

Air quality will remain dependent on smoke movement and possible ozone increases later in the week.

08/02/2025 Forecast Update

Ozone:
Ozone concentrations are expected to range between Good (Green AQI) and Moderate (Yellow AQI).

PM-2.5 (Fine Particulate):
PM-2.5 concentrations are expected to remain in the Unhealthy for Sensitive Groups (USG, Orange AQI) range, with some areas reaching Unhealthy (Red AQI) levels.

Forecast Discussion:
After a brief improvement in air quality across the Lower Peninsula on Friday, wildfire smoke is expected to return as winds shift back to a northwesterly flow. The Upper Peninsula experienced USG concentrations Friday, with only a short period of relief in the eastern regions.

Today (Saturday) and tomorrow (Sunday), smoke plumes will move southward, impacting the entire state once again. Elevated PM2.5 levels are anticipated across Michigan through the weekend.

Ozone levels are projected to stay within the Good to Moderate range for now. However, as this smoke episode comes to an end early next week, conditions will be monitored closely. Historically, lingering smoke can enhance ozone formation. If ozone concentrations appear likely to exceed USG levels, they will be incorporated into the ongoing forecast updates.

Extended Forecast:
Wildfire smoke and elevated PM2.5 concentrations are expected to persist through the weekend. Forecast updates will continue daily until this smoke event concludes.

07/31/2025 Forecast Update

Thursday, July 31, 2025 – Friday, August 1, 2025

Ozone:
8-hour ozone concentrations are expected to range between Good (Green AQI) and Moderate (Yellow AQI).

PM-2.5 (Fine Particulate):
24-hour daily average concentrations will mostly remain in the Unhealthy for Sensitive Groups (USG, Orange AQI) range, with Unhealthy (Red AQI) concentrations possible in some areas.

Air Quality Advisory: Thursday through Saturday
The Michigan Department of Environment, Great Lakes, and Energy (EGLE) has issued an Air Quality Advisory for elevated levels of fine particulate (PM2.5) across all Michigan counties. PM2.5 concentrations are expected to remain in the USG (Orange AQI) range, with some locations reaching the Unhealthy (Red AQI) range through Saturday.

Forecast Discussion:
Smoke from Canadian wildfires will persist over Michigan on Thursday, keeping PM2.5 levels elevated. While some improvement in air quality is possible in the Lower Peninsula late Thursday into Friday, conditions are expected to worsen again as additional smoke moves into the region. High pressure overhead will limit smoke dispersion, maintaining USG-level pollution and increasing the chance of localized Unhealthy readings through Saturday.

Ozone levels are expected to stay within the Moderate range due to cooler temperatures; however, the presence of surface smoke could cause unexpected increases. Ozone forecasts will be closely monitored through the weekend.

Extended Forecast:
Comfortable weather with sunshine is expected in the extended forecast. We will continue to monitor smoke impacts and adjust pollution forecasts as needed.

Next Forecast Update:
Friday, August 1, 2025

07/30/2025 Forecast Update

Pollutant Overview

Ozone Forecast:

8-hour ozone concentrations are expected to range between Good (Green AQI) and Moderate (Yellow AQI). Cloud cover and cooler air will help limit ozone levels, though smoke may cause localized increases.

PM-2.5 Forecast (Fine Particulates):

24-hour average PM-2.5 concentrations will increase into the Unhealthy for Sensitive Groups (USG, Orange AQI) range across Michigan. Some locations, especially in northern areas, may see Unhealthy (Red AQI) levels as smoke from Canadian wildfires moves through the state.

Air Quality Advisory:

An Air Quality Advisory is in effect for all Michigan counties on Wednesday and Thursday due to elevated levels of fine particulate (PM2.5). This will be re-evaluated Thursday morning to determine if an extension is needed.

Forecast Discussion:

Smoke from Canadian wildfires entered northern Michigan Tuesday and will continue spreading southward through Thursday. A cold front will aid in pulling this smoke further into the state. High pressure settling in behind the front will bring north to northeast winds, continuing the influx of smoke and potentially trapping it near the surface.

Ozone levels are expected to remain in the Good to Moderate range due to cooler temperatures, cloud cover, and precipitation, though localized increases are possible in areas with persistent surface smoke.

Extended Forecast:

Pleasant weather is expected as we move toward the weekend, but lingering smoke may continue to influence air quality. Conditions will be monitored closely.

Next Forecast Update:

Thursday, July 31, 2025

07/29/2025 Forecast Update

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

07/28/2025 Forecast Update

Pollutant Overview

Ozone (O₃):
8-hour average ozone concentrations are expected to range from Good (Green AQI) to Moderate (Yellow AQI). A small chance exists for Unhealthy for Sensitive Groups (USG, Orange AQI) levels in southern Michigan.

Fine Particulates (PM-2.5):
24-hour average concentrations will be mostly Moderate (Yellow AQI) statewide. USG levels are possible in the Upper Peninsula on Tuesday due to wildfire smoke.

Forecast Discussion

A weak frontal boundary will gradually move through Michigan between late Monday and Wednesday, bringing opportunities for scattered thunderstorms. Ahead of this front, hot and muggy conditions will continue across much of the state.

Relief from the heat is expected past mid-week as high pressure from Canada sinks southward, ushering in cooler and less humid air along with more comfortable temperatures for the latter half of the week.

For air quality:

• PM2.5 levels on Monday morning were ranging between upper Good and low Moderate, and similar levels are expected into Tuesday. However, the Upper Peninsula may experience increasing PM2.5 concentrations on Tuesday as wildfire smoke enters the region. Forecast updates will evaluate if these levels will rise enough to warrant an advisory.

• With high pressure expected to settle in later this week, there is potential for smoke to linger and become trapped near the surface, which we will continue to monitor.

For ozone:

• A fair amount of sunshine is expected on Monday and Tuesday, with hot and humid conditions in place, especially across central and southern Michigan.

• While humidity generally limits ozone formation, isolated areas could still reach low-end USG levels.

• By Wednesday, air quality conditions should improve as northerly winds push through behind the front.

Extended Outlook

The extended forecast calls for comfortable temperatures and plentiful sunshine through the end of the week. However, smoke presence will continue to be evaluated to determine any lingering impact on air quality.

Next Forecast Update: Tuesday, July 29, 2025

07/24/2025 Forecast Update

Pollutant Overview

Ozone (O₃):
8-hour average ozone concentrations are expected to range from Good (Green AQI) to Moderate (Yellow AQI). A small chance for USG (Orange AQI) exists in southeastern and southwestern Michigan on Thursday.

Fine Particulates (PM-2.5):
PM2.5 concentrations will be Moderate across southern Michigan, with USG levels developing in the Upper Peninsula Thursday afternoon, expanding into the northern Lower Peninsula by early Friday morning. There is a possibility of short-term Unhealthy (Red AQI) spikes in localized areas.

Forecast Discussion

A frontal boundary advancing south through Michigan will be the focal point for storm development and air quality impacts over the next few days.

• Thursday: Warm and humid conditions persist with sunshine and temperatures reaching 80s in the north and 90s in the south. Heat indices may approach 100°F in parts of southern Michigan.

• Precipitation will move into northern areas late Thursday, spreading further south by early Friday as the front progresses.

As the front moves south, Canadian wildfire smoke will be pulled into Michigan. Forecast models indicate:

• Smoke entering the Upper Peninsula Thursday afternoon

• The smoke plume will drift into the northern Lower Peninsula early Friday morning, potentially reaching central areas by midday Friday.

PM2.5 levels are expected to rise into the USG (Orange AQI) range in the advisory areas. There is also a chance for hourly concentrations to briefly reach the Unhealthy (Red AQI) range. The advisory will be reevaluated Friday morning to determine if expansion further south or an extension into Saturday is necessary.

For ozone, some monitors reached low-end USG levels in southeastern Michigan on Wednesday. A similar risk exists for Thursday, particularly in southeastern and southwestern Michigan, though most areas are expected to remain in the Moderate range.

Extended Outlook

The extended forecast remains uncertain due to:

• The path and intensity of additional smoke plumes

• The timing of precipitation

• The ongoing impact of heat and humidity on air quality levels

Further forecast updates will be issued as conditions develop.

07/23/2025 Forecast Update

Pollutant Overview

Ozone (O₃):
8-hour average ozone concentrations are expected to range from Good (Green AQI) to Moderate (Yellow AQI). A small chance exists for Unhealthy for Sensitive Groups (Orange AQI), particularly in parts of southern Lower Michigan.

Fine Particulates (PM-2.5):
24-hour average concentrations will remain mostly Moderate (Yellow AQI) statewide, with potential increases due to wildfire smoke later in the forecast period.

Forecast Discussion

A frontal boundary is progressing south through Michigan, bringing a shift in weather and air quality conditions:

• On Wednesday, the front will bring precipitation to the Upper Peninsula and parts of Northern Lower Michigan, while sunny skies continue further south.

• Temperatures will rise into the 80s on Wednesday and climb into the 90s on Thursday across much of the Lower Peninsula.

• Heat indices may approach 100°F in the south on Thursday. With the increasing humidity, outdoor conditions will become uncomfortable, and heat safety precautions are advised.

For air quality:

• PM2.5 levels have remained in the upper Good to low Moderate range, and similar levels are expected through Wednesday.

• Smoke models suggest a plume of wildfire smoke may move into the Upper Peninsula Thursday afternoon, gradually pushing into southern Michigan by late Thursday into Friday. If current trends continue, PM2.5 may approach USG levels in affected regions. This will be closely monitored for potential air quality alerts.

• Ozone levels are forecast to remain Moderate, with Good conditions in the north. Sunshine and warming temperatures may allow for localized increases on Wednesday, but increased humidity and cloud cover Thursday will likely limit ozone formation. A small chance exists for isolated USG levels, though not enough to warrant a pollution alert at this time.

Extended Outlook

There is continued uncertainty in the extended forecast regarding:

• The timing and intensity of precipitation

• The trajectory of additional smoke plumes

• The influence of lingering heat and humidity on pollutant levels

Further forecast updates will provide additional detail as conditions evolve through the end of the week.

07/22/2025 Forecast Update

Pollutant Overview

Ozone (O₃):
8-hour average ozone concentrations are expected to range from Good (Green AQI) to Moderate (Yellow AQI). A small chance for Unhealthy for Sensitive Groups (Orange AQI) exists, particularly in southern areas.

Fine Particulates (PM-2.5):
24-hour average concentrations will be mostly Moderate (Yellow AQI) statewide, with some influence from surface-level smoke.

Forecast Discussion

Two key features are shaping Michigan's weather between Tuesday and Wednesday:

• A high-pressure system positioned east of the state will keep conditions mostly quiet.

• A frontal boundary to the northwest will begin bringing precipitation to the western Upper Peninsula later Tuesday. This front will slowly move south through Thursday, eventually impacting the Lower Peninsula with potential rain and storms.

In the meantime, temperatures will climb into the 80s and 90s, and humidity levels will rise, creating more uncomfortable outdoor conditions as the week progresses.

As for air quality:

• Fine particulate levels (PM2.5) will remain mostly Moderate, as lingering smoke from Wisconsin and Lake Michigan shifts back over the region. No significant spikes are expected.

• Ozone concentrations may also increase slightly due to this smoke, but rising dew points will likely help limit formation. A small chance for USG ozone levels exists in southern Michigan, though Good to Moderate conditions are expected across most areas.

Extended Outlook

Smoke model data suggests another potential smoke intrusion behind the frontal boundary on Thursday, which could impact air quality later in the week.

There remains uncertainty in the extended forecast regarding:

• Timing of precipitation

• Duration of lingering heat

• Potential for wildfire smoke return

Future updates will provide more detail as conditions develop.

07/21/2025 Forecast Update

Pollutant Overview

Ozone (O₃):
8-hour average ozone concentrations are expected to remain Good (Green AQI) to Moderate (Yellow AQI). There is a small chance of Unhealthy for Sensitive Groups (Orange AQI) at select southern Michigan monitors on Tuesday afternoon.

Fine Particulates (PM-2.5):
24-hour average concentrations will be mostly Moderate (Yellow AQI), with improving conditions across southern Michigan as lingering wildfire smoke clears.

Forecast Discussion

Fine particulate concentrations increased across Michigan late Sunday into early Monday due to a north-to-south moving wildfire smoke plume. Hourly PM2.5 levels reached the USG (Orange AQI) range in parts of the southwest, but daily averages remained Moderate across the state.

High pressure will remain in control through Tuesday, bringing plenty of sunshine, comfortable temperatures, and low humidity. Beginning Wednesday, high pressure will shift east as an upper-level ridge (heat dome) builds over the southeastern U.S., bringing hotter, more humid air into Michigan by midweek. A boundary approaching from the north will introduce storm chances beginning Wednesday or Thursday.

For air quality:

• PM2.5 levels are expected to improve on Monday, with Good conditions in northern areas and Moderate in the south. Lingering smoke may lead to continued Moderate levels on Tuesday, but higher concentrations are not expected.

• Ozone levels will range from Good to Moderate, though surface smoke may enhance ozone formation in some areas. A few southern monitors could briefly reach USG (Orange AQI) levels Tuesday afternoon.

We will continue monitoring conditions and will update the forecast if ozone levels appear likely to rise further as heat and humidity build midweek.

Extended Outlook

Uncertainty remains regarding additional wildfire smoke moving into the region with the expected frontal boundary later this week. Forecasts will be updated accordingly as conditions evolve.

07/18/2025 Forecast Update

Pollutant Overview

Ozone (O₃):

8-hour average concentrations are expected to remain Good (Green AQI), with scattered periods of Moderate (Yellow AQI) throughout the forecast period.

Fine Particulates (PM-2.5):
24-hour average concentrations are also expected to be Good (Green AQI) overall, with isolated instances of Moderate (Yellow AQI).

Forecast Discussion

A cooler, drier air mass will settle over Michigan following Thursday’s clouds. Friday will feel refreshing, with highs near 80°F and no wildfire smoke in the region—setting the stage for excellent air quality to begin the weekend.

Saturday brings a chance of thunderstorms and potential severe weather. Morning showers could reduce afternoon storm intensity by limiting instability. However, if the morning stays dry, the likelihood of stronger afternoon storms increases. Regardless, Saturday is likely to be wet.

Sunday will see a return to sunny skies and comfortable temperatures in the low 80s, accompanied by light north-northeast winds. Air quality is expected to remain mostly Good for both ozone and fine particulates.

Looking ahead, summer weather returns midweek, with temperatures possibly reaching the low 90s and continuing into the following weekend.

Extended Outlook

Air quality is not expected to be an issue as the upcoming work week begins.