10/27/2025 Air Quality Forecast

FORECAST SUMMARY: Monday, October 27, 2025 through Friday, October 31, 2025

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

 PM-2.5: 24-hour average Fine Particulate concentrations are expected to be Good (AQI Green) to scattered Low Moderate (AQI Yellow).

  FORECAST DISCUSSION

 As we wind up October, we also wind up the 2025 Ozone season.  In recap, although it was a warmer summer, elevated ozone days were below normal.  A good thing!  The wildfire season certainly gave us fits, so it was nice to have a relatively good ozone season.

 We are at the time of year where Air Quality generally does not cause any problems.  Ozone season is ending, and Canadian wildfires are in retreat.  Weather patterns can still be active, however, and hurricane season is still raging in the Caribbean. 

 The weather for this week is expected to be seasonal and mostly dry for the first half of the week.  A retreating high-pressure system is giving way to an approaching low-pressure system predicted to move up the Mississippi/Ohio River valleys later in the week.

 The retreating high-pressure will continue to provide clear skies through Wednesday as the low-pressure system drives northeast through the Mississippi/Ohio River valleys.  Being sandwiched between the high-pressure and low-pressure cells will give us brisk easterly winds through much of the early half of the week.  As the low-pressure cell passes beneath us later in the week, we will have the best shot at some Halloween precipitation although not predicted to be heavy.

  EXTENDED FORECAST:

 Air Quality is expected to remain Good to Low Moderate entering the upcoming work week.

10/24/2025 Air Quality Forecast

FORECAST SUMMARY: Friday October 24th, 2025, through Monday October 27th, 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 low-Moderate (Yellow AQI) range.

FORECAST DISCUSSION:

A Pure Michigan Fall weekend is ahead for the last weekend of October with clear skies and temperatures right around seasonal norms. After a few days of dreary and rainy weather, dry air via high-pressure moved in overnight which is reasoning for why most of us are under blue skies this Friday morning.

This high-pressure will persist through the weekend providing light winds and easterly to southeasterly flow which will keep our surface temperatures right what seasonal averages for this time of year. Going into Saturday night, it appears some precipitation tries to develop but a dominating dry airmass will dissipate any chance for precipitation to fall. Speaking of Saturday night, whether you are a Michigan fan or Michigan State fan (Go Blue!) it will be perfect football weather for the two rivals to square off in East Lansing. More of the same on Sunday as the high-pressure hangs around throughout the weekend and into the start of the next work week.

For air quality, there is one more full week for the official Ozone season as Ozone continues to be a nonissue as our surface temperatures continue to slowly decrease. With light winds in place, especially during the mornings, it would not be surprising to see an increase of PM-2.5 concentrations in the populated areas. As each day carries on, however, these concentrations are expected to decrease.

EXTENDED FORECAST:

The last full work week of October starts off with seasonal average temperatures and clear skies. Air quality will continue to remain in the Good range.

Next Forecast update: Monday October 27th, 2025

10/20/2025 Air Quality Forecast

FORECAST SUMMARY: Monday October 20th, 2025, through Friday October 24th, 2025

Ozone:

Ozone concentrations are expected to be in the Good (Green AQI) range.

PM-2.5:

PM-2.5 concentrations are expected to be in the Good (Green AQI) to low-Moderate (Yellow AQI) range.

FORECAST DISCUSSION:

After a rather wet and dreary weekend, Michiganders wake up to some sunshine and quiet conditions this Monday morning. Currently we are in a lull period between two systems with the second system expected to impact us tomorrow, Tuesday, and into Wednesday. Rainy conditions return to the entire state later on Tuesday after a cold front moves through earlier in the day. This will drop temperatures down to around seasonal norms and shift our wind direction to more northwesterly. With the upper 40s being forecasted as high temperatures on Wednesday, and lake temperatures still in the upper 50s, lake-effect rain showers will impact the state predominantly on Wednesday. This is the same process as lake-effect snow, but with temperatures still a bit above freezing, the form of precipitation will be rain. Lingering lake-effect showers persist into Thursday before we dry out on Friday and head into the weekend.

For air quality, there are two more weeks left in the official Ozone season as Ozone does not look to be a threat this week as temperatures hang around in the 40s to 50s. Aside from early morning commutes, PM-2.5 does not look to be a threat either as breezy conditions return midweek which will help to clean out any particulate build up.

EXTENDED FORECAST:

The ending of this week persists through the weekend with seasonal norms on the docket. Air quality is expected to remain in the Good range.

Next Forecast update: Friday October 24th, 2025

10/13/2025 Air Quality Forecast

FORECAST SUMMARY: Friday October 17th, 2025, through Monday October 20th, 2025

Ozone:

Ozone concentrations are expected to be in the Good (Green AQI) range.

PM-2.5:

PM-2.5 concentrations are expected to be in the Good (Green AQI) to low-Moderate (Yellow AQI) range.

FORECAST DISCUSSION:

After numerous weekends of picture-perfect, above normal Fall weekends, us Michiganders are in store for a rather opposite weekend ahead: rainy and windy. Some areas in the north will see rain tapering off this Friday afternoon with a clear evening for most of us. Come Saturday, however, the majority of the Great Lakes region will be impacted by a Low-pressure system making its way into the area, which will be influencing our day-to-day for the remainder of the weekend. A quick-hitting warm front will move through the area early Saturday morning which will provide above-normal temperatures during the day on Saturday, before temperatures drop come Saturday evening with a trailing cold front. In between the two fronts, rain will be hit or miss in most areas with wind gusts increasing throughout Saturday afternoon and evening. Come Sunday, the ‘Gales of November’ look to come early as the Low-pressure system moves over top of Michigan providing gusty conditions across the Great Lakes. This is due, in part, to the aforementioned Low-pressure system and a High-pressure system out to the east, so the pressure gradient will be sandwiched between the two, causing the windy conditions. With the Low-pressure over us on Sunday, persistent rain across the state, coupled with windy conditions, will make for a great inside-kind-of-day.

For air quality, Good concentrations are expected throughout the weekend with Ozone not being a threat due to cloudy conditions and cooler temperatures. The windy conditions will also help to keep PM-2.5 concentrations in the Good range due to ample dispersion and a clean air mass.

EXTENDED FORECAST:

Breezy conditions continue into next week with a slight increase in temperatures before dropping down to seasonal norms. Air quality will remain in the Good range.

Next Forecast update: Monday October 20th, 2025

10/10/2025 Air Quality Forecast

FORECAST SUMMARY: Friday, October 10, 2025 through Monday, October 13, 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 expected to be Good (AQI Green) to scattered Low Moderate (AQI Yellow).

FORECAST DISCUSSION

In many ways, this weekend will be much like last weekend with the difference being some 20 degrees cooler. Once we get past some rain chances this evening, thanks to a passing cold front, clear skies and dry air returns thanks to the next high-pressure system building in behind the front.

This week felt more like traditional fall weather with daily highs in the 60’s and chilly 30 degrees weather at night.  Some light frost occurred in low lying areas and roof tops but no killing frost.  The rain expected Friday evening should be light in nature as this system does not have a great deal of moisture.  Rainfall amounts are expected, however, to increase the further north you go.

Once the approaching high pressure pushes out the Friday night cold front, clear skies and slightly warmer temperatures settle in.  Clear skies with daily highs in the upper 60’s and low 70’s with nighttime temperatures in the 40’s should persist for most of the upcoming work week. 

In terms of Air Quality, I am not anticipating any issues during this period and AQI levels should range between mostly Good to scattered Low Moderate.

EXTENDED FORECAST:

 Air Quality is expected to remain Good to Low Moderate entering the upcoming weekend.

10/06/2025 Air Quality Forecast

FORECAST SUMMARY: Monday, October 6, 2025 through Friday, October 10, 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 expected to be Good (AQI Green) to scattered Low Moderate (AQI Yellow).

 FORECAST DISCUSSION

 In the spirit of “All Good Things Must Come to an End”, Monday will be the last day of the extended late summer weather we have been enjoying.  Current temperatures, running 15-20 degrees above normal, will come to an end as an advancing cold front migrates through the region Monday night and Tuesday. 

 This front will collide with deep moisture streaming up from the Gulf.  Atmospheric instability is limited, but models are showing some convection which could contain brief heavy downpours and gusty winds.  Heaviest precipitation looks to be in a line stretching from Holland to the northern Thumb area.  Rainfall amounts in this zone will likely range from three-quarters inch to an inch.  Other areas should expect about half an inch of rain.

 High pressure will move in Tuesday evening with dry, northerly flow and more seasonable temperatures.  With clear skies and dry conditions, we can expect high temperatures in the mid-60’s and low temperatures in the upper 30’s and low 40’s.  Remote low-lying areas could see some light frost.  These conditions should prevail through the remainder of the forecast period.

 In terms of Air Quality, I am not anticipating any issues during this period and AQI levels should range between mostly Good to scattered Low Moderate.

 EXTENDED FORECAST:

 Air Quality is expected to remain Good to Low Moderate entering the upcoming weekend.

10/03/2025 Air Quality Forecast

FORECAST SUMMARY: Friday, October 3, 2025 - Monday, October 6, 2025

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

PM-2.5: 24-hour daily average Fine Particulate concentrations will average mostly Moderate.

FORECAST DISCUSSION:

The big story for this forecast period will be the unseasonably warm temperatures. Highs today (Friday) through Sunday are forecast to reach into the 80s across most of the state. This is due to high pressure and southerly winds, which increase as the weekend progresses. As the new week starts, a frontal boundary will be moving into the Upper Peninsula. As this system moves in, it brings with it some much-needed rain Monday up north, pushing south later Monday into Tuesday.

As for air quality, the warm surface and upper-level temperatures could allow for Moderate ozone levels this forecast period. However, with it being so late in the season, readings higher than Moderate are not anticipated. Southerly winds will also allow fine particulates to increase, with mostly Moderate levels expected through the period.

EXTENDED FORECAST:

Extended models show a cold front passing northwest to southeast through the state Monday. This boundary brings with it precipitation and cooler temperatures. Air quality in the Moderate range should improve back towards the Good range on Tuesday.

Next Forecast update: Monday, October 6, 2025 

9/29/2025 Air Quality Forecast

FORECAST SUMMARY: Monday, September 29, 2025 - Friday, October 3, 2025

Ozone: 8-hour ozone concentrations are expected to range mostly Good (Green AQI), with some scattered Moderates (Yellow AQI) possible.

PM-2.5: 24-hour daily average Fine Particulate concentrations will average between Good and Moderate.

FORECAST DISCUSSION:

As September ends and we move into October, warm and dry conditions continue across Michigan. Upper-level ridging and surface high pressure are the dominating weather features this week aside from a weak, dry front passing north to south on Tuesday. Temperatures behind this boundary will decrease to around 70 degrees between Tuesday and Thursday; otherwise, highs around 80 degrees are likely. Clear skies allow for favorable radiational cooling at night, and lows through the week range between the mid-40s and low-50s.

Air quality is not expected to be an issue during this forecast period, and we anticipate that AQI levels will range from Good to low-Moderate.

EXTENDED FORECAST:

Extended models show a cold front possibly bringing precipitation to northern locations this coming weekend. Warmer temperatures continue in the long term, with air quality concentrations remaining between Good and low-Moderate.

Next Forecast update: Friday, October 3, 2025

9/26/2025 Air Quality Forecast

FORECAST SUMMARY: Friday, September 26, 2025 through Monday, September 29, 2025

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

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

FORECAST DISCUSSION

After a mostly cloudy and wet week, conditions are shaping up to be a nice late-summer type of weekend.  After a weak low-pressure system exits the area on Friday, we will see a drying out period with low humidity and warming temperatures.

 I expect those warming temperatures to prevail through the mid-levels of the atmosphere with high-pressure dominating the region and the lack of moisture keeping most of the area dry and clear.  Afternoon high temperatures are expected in the upper-70’s and low-80’s under sunny skies with nighttime temperatures under clear skies in the mid-50’s.  Indications are that this pattern will last through the middle part of next week.

 In terms of Air Quality, I am not anticipating any issues during this tranquil period and AQI levels should range between Good and Moderate through the forecast period.

  EXTENDED FORECAST:

 Air Quality is expected to remain Good to Low Moderate entering the upcoming work week.

9/22/2025 Air Quality Forecast

FORECAST SUMMARY: Monday September 22, 2025, through Friday September 26, 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:

Much needed rain has been intermittently falling across the state for the past 24 hours with spotty rain showers expected to persist through midweek. Continuous Low-pressure systems and associated frontal boundaries look to sit over Michigan today, Monday, through Wednesday night before moving off to the east come Thursday morning. Surface temperatures slightly above seasonal norms are expected this week as well, with the exception of Wednesday, which is due to rain showers throughout the day on Wednesday. A total washout is not expected with rain totals Thursday morning expected to hover around the half inch to inch mark for areas across the lower peninsula. The upper peninsula has been receiving rain rather frequently compared to the lower peninsula and that can be seen on the drought map as the majority of the lower peninsula is in some form of drought stage. After the rain moves off to the east, however, clearing skies return for Thursday and Friday with surface temperatures returning to the mid-to-high 70s.

For air quality, the cloudy, rain skies coupled with cooler temperatures will keep Ozone concentrations at bay unlike last week where a few high-Moderate and even some Unhealthy for Sensitive Groups concentrations were observed due to the warmer temperatures. That will not be the case this week as we move closer to the end of Ozone season. Aside from morning commutes increasing PM-2.5 values, PM-2.5 concentrations do not look to be an issue this week either with Good to low-Moderate concentrations expected.

EXTENDED FORECAST:

Clearing skies and warmer temperatures return for the weekend ahead. Air quality should range between the Good and Moderate range.

Next Forecast update: Friday September 26th, 2025

9/19/2025 Air Quality Forecast

FORECAST SUMMARY: Friday, September 19, 2025 through Monday, September 22, 2025

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

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

FORECAST DISCUSSION

As of Friday morning, Michigan lies beneath an upper-level ridge with a digging low-pressure trough across the northern plains.  As the upper-level ridge advances eastward, the low-pressure trough will work its way into our region during the weekend.  A warm front associated with the approaching trough will work its way through Saturday morning and afternoon, which will likely bring some showers and storms to the area with the best chances along the western lakeshore.  Better chances for precipitation arrive Saturday night into Sunday with chances for precipitation lingering through Monday.

In terms of Air Quality, I am not anticipating any issues and AQI levels should range between Good and Moderate through the forecast period.

Fall officially arrives on Monday September 22.  Farewell summer 2025…  With the exception of the wildfire smoke, you will be missed!

 EXTENDED FORECAST:

 Air Quality is expected to remain Good to Moderate entering the upcoming work week.

9/15/2025 Air Quality Forecast

FORECAST SUMMARY: Monday, September 15, 2025, through Friday, September 19, 2025

 OZONE: 8-hour average Ozone concentrations are expected to be mostly Good (AQI Green) to Low Moderate (AQI Yellow).  There is a slight chance of isolated USG (AQI Orange).

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

  FORECAST DISCUSSION

 The last full week of summer will feature summer-like weather with temperatures reaching the mid to upper 80’s with low humidity and clear skies.  Ideal weather to be outside before the cooler weather of Fall arrives.

 This time of year usually produces Good Air Quality.  Wildfire smoke is currently contained to the northern provinces of Canada is not presenting a problem.  Ozone production is still possible, as we saw a few scattered, single monitor Low USG readings, last week.  However, since the days are getting shorter and the nights are getting cooler, no widespread USG conditions are expected.  It is possible that an isolated monitor could reach Low USG, however.

 The 7-day forecast has the current weather pattern remaining in place.  With no turnover in air mass we can expect fine particulates to accumulate but no worse than the Moderate levels of the AQI are expected.  As mentioned above, ozone production could yield some isolated Low USG readings, but widespread Moderate readings are more likely.

  EXTENDED FORECAST:

 Air Quality is expected to remain Good to Moderate entering the upcoming weekend.

9/12/2025 Air Quality Forecast

FORECAST SUMMARY: Friday, September 12, 2025, through Monday, September 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 Good (Green AQI) to Moderate (Yellow AQI) range.

FORECAST DISCUSSION:

Fair weather clouds, mostly sunny skies and surface temperatures reaching the 80s is what Michiganders have in store for this Friday. High-pressure sits both to our northeast and southeast, providing warm and sunny conditions. The only real hindrance in the upcoming forecast is tomorrow, Saturday, with scattered to spotty showers possible for southern Michigan as a weak frontal boundary approaches the state, it will not be a complete washout, however. Surface temperatures will range in the mid-70s for the majority of the state, with overcast to partly cloudy skies throughout the day. Come Sunday, although, we are back under High-pressure with clearing skies and making a run at 80-degree temperatures across the state. Monday and into next week, this trend continues as warmer temperatures return to the Great Lakes.

For air quality, with surface temperatures reaching the 80s, coupled with light winds, Ozone may pose a threat with concentrations reaching the high-Moderate range in both southwest and southeast Michigan, with the possibility of an hourly concentration in the Unhealthy for Sensitive Groups (USG) range. These concentrations in the USG range should not be widespread, however. It is not uncommon for USG-level Ozone concentrations in the month of September, but decreasing sunlight and an unfavorable sun angle, makes it hard for Ozone to produce. With even warmer temperatures next week, Ozone will be looked at more closely. PM-2.5 concentrations will continue their trend of Good to Moderate concentrations, especially for more populated areas like Grand Rapids and Detroit. Southerly flow later this weekend may increase concentrations into the mid-Moderate range, but only for a few hours before decreasing.

EXTENDED FORECAST:

Summer-like temperatures return next week as the mid-to-upper 80s are on the horizon for areas across Michigan. Air quality, as of now, will remain in the Good to Moderate range.

Next Forecast update: Monday, September 15, 2025

9/05/2025 Air Quality Forecast

FORECAST SUMMARY: Friday September 5th, 2025, through Monday September 8th, 2025

Ozone:

Ozone concentrations are expected to be in the Good (Green 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 breezy Friday morning and afternoon will kick off the first weekend of September with surface temperatures ranging from the upper-50s to mid-60s throughout the weekend. A Low-pressure system started to traverse across the Great Lakes region early Friday morning and is the reasoning behind the breezy conditions. The gradient of pressure within the atmosphere as the Low-pressure moves through is being compressed, which in turn produces windy conditions with the possibility of strong gusts. After all, wind speed and gusts are directly correlated with how tight the pressure gradient is within the atmosphere.

Going into Saturday, winds will continue to slow down as the aforementioned Low-pressure moves further east, and the skies will open up to more sunshine. Even though it is not astronomical Fall, it is technically meteorological Fall, and it very much will feel like Fall Saturday and into Sunday with highs in the mid-60s at best. Sunday will essentially be a copy and paste of Saturday with light to moderate winds. Due to the cooler temperatures and wind direction being predominantly west-northwesterly, lake-effect pop-up rain showers should be expected throughout the weekend as well. Just like lake-effect snow, the lake waters are warmer than the surrounding air, so the same mechanism of lake-effect snow takes place, but in this case, the surface air is still in the 50s and 60s, so precipitation will fall in the form of rain. As said above though, these will be sporadic and should not last long.

For air quality, the cooler temperatures will continue to keep Ozone concentrations at bay as we are closing in on the end of the Ozone season. For PM-2.5, a small and rather light plume of smoke is currently in the Midwest this Friday morning as monitors across the region are reading in the Moderate range. With the windy conditions in place, this plume will move out rather quickly. Throughout the rest of the weekend, however, Good PM-2.5 concentrations are expected with the exception of early morning light winds allowing for particulate build up in the more populated areas of metro Detroit and Grand Rapids.

EXTENDED FORECAST:

Temperatures return to the 70s next week with a small possibility of some wildfire smoke returning, but nothing more than Moderate concentrations as of right now. Air quality will be in the Good to Moderate range.

Next Forecast update: Monday September 8th, 2025

9/02/2025 Air Quality Forecast

FORECAST SUMMARY: Tuesday September 2nd, 2025, through Friday September 5th, 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:

We enter the first full week of September with the official start of Meteorological Fall passing on September 1st, providing near-normal temperatures today, Tuesday, and a cool down later this week.

Tuesday will be an extension of the beautiful weather we had over the holiday weekend with temperatures in the 70s and ample sunlight. This is due to a High-pressure system sitting just to our southwest funneling in clear skies and warm air. Come midweek, however, this pattern will give way to a Low-pressure system and associated cold front that will cool us down into the 60s for southern Michigan and the 50s for the upper peninsula. With this cold front, rain showers are expected Wednesday morning through early Thursday afternoon as the cold front traverses through the state from the northwest to the southeast. On the backside of the cold front, will be a High-pressure system replacing the mid-to-late week weather regime, which will provide sunny conditions, albeit cooler. It will truly feel like Fall this upcoming weekend with temperatures ranging from the 50s to the mid-60s.

For air quality, with the cooler temperatures in place, along with shifting weather patterns, Ozone will continue to be a non-issue as the photochemical reaction that takes place to form Ozone will not have the proper ingredients to initiate. For PM-2.5, a few long-term smoke models are showing some amounts of wildfire smoke making its way down into the Midwest later this week and into the weekend. Nothing more than the Moderate range in terms of concentrations, as of now, are expected. So, in all, air quality is expected to range in the Good to Moderate range for the remainder of this week.

EXTENDED FORECAST:

As mentioned above, Fall-like weather is expected for the first full weekend of September with air quality remaining in the Good to Moderate range.

Next Forecast update: Friday September 5th, 2025

8/29/2025 Air Quality Forecast

FORECAST SUMMARY: Friday, August 29, 2025, through Tuesday, September 2, 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) to scattered Low Moderate (AQI Yellow).

  FORECAST DISCUSSION

Cooler than normal weather will continue into the holiday weekend but will gradually climb back to the normal range of around 80 degrees by Monday.  Night temperatures will continue to run below normal for chilly evenings.  Clear skies make for warming during the day but quickly lose that heat, at night, without the cloud cover.  This cool, dry weather trend is due to a surface high pressure cell building over the central Great Lakes. 

The cool, dry weather should persist through the Labor Day weekend and into early next week with the next chance of rain coming during Wednesday.

These factors will lead to continued Good Air Quality with the possibility of scattered Low Moderate developing in Southeast Michigan by the end of the forecast period.

  EXTENDED FORECAST:

 Air Quality is expected to remain Good to Low Moderate entering the next work week.

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