SmogRank / Episodes / United States

Northern United States, August 2025

For 1 day, on 11 August 2025, 13 cities in the United States and Canada had PM2.5 at least twice their usual for the time of year. The worst reading was Winnipeg, Manitoba, Canada: 73.6 µg/m³ on 11 August, about 8.6× its usual 8.6.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached13in 2 countries
Days111 August 2025
Worst day11 August13 cities counted
Furthest above usual8.6×Winnipeg

Day by day

11 August 13 cities at twice their usual or more
Saint MichaelWatertownSaint PaulApple ValleyRochesterEau ClaireMadisonBurnsvilleMinneapolisShakopeeDuluthBlaineMankatoBrookingsSuperiorSaint CloudSioux FallsWest FargoAberdeenWinnipeg
8 Aug91011121314
Every measured city in the area, coloured by its PM2.5 that day; a dark ring marks a city at twice its usual or more. Bars: cities counted each day, coloured by their median level. Choose a day or press play; without JavaScript, the days link to that day's world ranking.

How it spread

WinnipegWinnipeg, 8 August: 91.0 µg/m³, 11× usualWinnipeg, 9 August: 10.2 µg/m³, 1.2× usualWinnipeg, 10 August: 6.8 µg/m³, 0.8× usualWinnipeg, 11 August: 73.6 µg/m³, 8.6× usualWinnipeg, 12 August: 26.5 µg/m³, 3.1× usualWinnipeg, 13 August: 25.3 µg/m³, 2.9× usualWinnipeg, 14 August: 14.6 µg/m³, 1.7× usualAberdeenAberdeen, 8 August: 4.8 µg/m³, 0.8× usualAberdeen, 9 August: 3.1 µg/m³, 0.5× usualAberdeen, 10 August: 33.5 µg/m³, 5.8× usualAberdeen, 11 August: 39.0 µg/m³, 6.7× usualAberdeen, 12 August: 6.3 µg/m³, 1.1× usualAberdeen, 13 August: 5.6 µg/m³, 1.0× usualAberdeen, 14 August: 4.1 µg/m³, 0.7× usualWest FargoWest Fargo, 8 August: 3.8 µg/m³, 0.4× usualWest Fargo, 9 August: 3.4 µg/m³, 0.4× usualWest Fargo, 10 August: 12.2 µg/m³, 1.3× usualWest Fargo, 11 August: 58.0 µg/m³, 6.1× usualWest Fargo, 12 August: 17.3 µg/m³, 1.8× usualWest Fargo, 13 August: 26.5 µg/m³, 2.8× usualWest Fargo, 14 August: 6.8 µg/m³, 0.7× usualSaint CloudSaint Cloud, 8 August: 10.2 µg/m³, 1.1× usualSaint Cloud, 9 August: 4.5 µg/m³, 0.5× usualSaint Cloud, 10 August: 9.1 µg/m³, 1.0× usualSaint Cloud, 11 August: 46.6 µg/m³, 4.9× usualSaint Cloud, 12 August: 9.0 µg/m³, 0.9× usualSaint Cloud, 13 August: 18.2 µg/m³, 1.9× usualSaint Cloud, 14 August: 13.1 µg/m³, 1.4× usualMankatoMankato, 8 August: 17.2 µg/m³, 1.7× usualMankato, 9 August: 10.9 µg/m³, 1.1× usualMankato, 10 August: 8.3 µg/m³, 0.8× usualMankato, 11 August: 38.2 µg/m³, 3.8× usualMankato, 12 August: 40.5 µg/m³, 4.1× usualMankato, 13 August: 17.3 µg/m³, 1.7× usualMankato, 14 August: 16.7 µg/m³, 1.7× usualSuperiorSuperior, 8 August: 18.6 µg/m³, 2.0× usualSuperior, 9 August: 11.5 µg/m³, 1.3× usualSuperior, 10 August: 12.6 µg/m³, 1.4× usualSuperior, 11 August: 37.7 µg/m³, 4.1× usualSuperior, 12 August: 20.2 µg/m³, 2.2× usualSuperior, 13 August: 31.3 µg/m³, 3.4× usualSuperior, 14 August: 29.4 µg/m³, 3.2× usualSioux FallsSioux Falls, 8 August: 10.1 µg/m³, 1.7× usualSioux Falls, 9 August: 2.9 µg/m³, 0.5× usualSioux Falls, 10 August: 11.2 µg/m³, 1.8× usualSioux Falls, 11 August: 32.9 µg/m³, 5.4× usualSioux Falls, 12 August: 19.5 µg/m³, 3.2× usualSioux Falls, 13 August: 5.6 µg/m³, 0.9× usualSioux Falls, 14 August: 5.9 µg/m³, 1.0× usualShakopeeShakopee, 8 August: 11.3 µg/m³, 1.1× usualShakopee, 9 August: 7.0 µg/m³, 0.7× usualShakopee, 10 August: 6.6 µg/m³, 0.7× usualShakopee, 11 August: 27.7 µg/m³, 2.8× usualShakopee, 12 August: 25.2 µg/m³, 2.5× usualShakopee, 13 August: 14.9 µg/m³, 1.5× usualShakopee, 14 August: 12.2 µg/m³, 1.2× usualMinneapolisMinneapolis, 8 August: 12.8 µg/m³, 1.3× usualMinneapolis, 9 August: 7.6 µg/m³, 0.8× usualMinneapolis, 10 August: 8.0 µg/m³, 0.8× usualMinneapolis, 11 August: 27.3 µg/m³, 2.7× usualMinneapolis, 12 August: 22.6 µg/m³, 2.3× usualMinneapolis, 13 August: 21.9 µg/m³, 2.2× usualMinneapolis, 14 August: 15.8 µg/m³, 1.6× usualBrookingsBrookings, 8 August: 11.3 µg/m³, 1.7× usualBrookings, 9 August: 3.0 µg/m³, 0.5× usualBrookings, 10 August: 14.4 µg/m³, 2.2× usualBrookings, 11 August: 26.7 µg/m³, 4.0× usualBrookings, 12 August: 12.6 µg/m³, 1.9× usualBrookings, 13 August: 7.6 µg/m³, 1.2× usualBrookings, 14 August: 6.3 µg/m³, 1.0× usualBlaineBlaine, 8 August: 10.4 µg/m³, 1.2× usualBlaine, 9 August: 6.7 µg/m³, 0.8× usualBlaine, 10 August: 7.6 µg/m³, 0.9× usualBlaine, 11 August: 26.3 µg/m³, 3.0× usualBlaine, 12 August: 17.3 µg/m³, 2.0× usualBlaine, 13 August: 21.1 µg/m³, 2.4× usualBlaine, 14 August: 15.5 µg/m³, 1.8× usualBurnsvilleBurnsville, 8 August: 11.9 µg/m³, 1.1× usualBurnsville, 9 August: 6.6 µg/m³, 0.6× usualBurnsville, 10 August: 5.9 µg/m³, 0.6× usualBurnsville, 11 August: 25.8 µg/m³, 2.4× usualBurnsville, 12 August: 27.7 µg/m³, 2.6× usualBurnsville, 13 August: 17.2 µg/m³, 1.6× usualBurnsville, 14 August: 14.5 µg/m³, 1.4× usualDuluthDuluth, 8 August: 11.6 µg/m³, 1.3× usualDuluth, 9 August: 7.3 µg/m³, 0.8× usualDuluth, 10 August: 7.9 µg/m³, 0.9× usualDuluth, 11 August: 25.6 µg/m³, 2.8× usualDuluth, 12 August: 13.8 µg/m³, 1.5× usualDuluth, 13 August: 23.7 µg/m³, 2.6× usualDuluth, 14 August: 23.2 µg/m³, 2.5× usual8 Aug91011121314
Every counted city, in the order the episode reached them, 3 days before to 3 after. Each square is a day, coloured by that day's PM2.5; outlined: at twice the city's usual or more.
Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

Every city it reached

CityDaysHighestUsualAbove usual
WinnipegManitoba, Canada1 91.08 August8.611×
AberdeenSouth Dakota, United States1 39.011 August5.86.7×
West FargoNorth Dakota, United States1 58.011 August9.56.1×
Sioux FallsSouth Dakota, United States1 32.911 August6.15.4×
Saint CloudMinnesota, United States1 46.611 August9.54.9×
SuperiorWisconsin, United States1 37.711 August9.14.1×
MankatoMinnesota, United States1 40.512 August10.04.1×
BrookingsSouth Dakota, United States1 26.711 August6.64.0×
BlaineMinnesota, United States1 26.311 August8.83.0×
DuluthMinnesota, United States1 25.611 August9.12.8×
ShakopeeMinnesota, United States1 27.711 August10.02.8×
MinneapolisMinnesota, United States1 27.311 August10.02.7×
BurnsvilleMinnesota, United States1 27.712 August10.62.6×

Daily means in µg/m³. Usual: the city's median for this time of year (its days within 21 days of the date, every year, leaving out the week around it). Above usual: its highest day against that.

Against other episodes in the United States and Canada

Number 65 of 106 episodes in the United States and Canada since our records began, by cities reached.

Bars: cities reached; colour: the level of the episode's highest daily reading. All 106.

Use this page

SmogRank, Northern United States, August 2025: 13 cities with PM2.5 at twice their usual or more, 11 August 2025, smogrank.com/episodes/2025-08-northern-united-states (accessed 2 October 2026).

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You're welcome to reuse a single chart, image or figure with this citation and a link. Terms.

An episode is a run of days when many cities close to each other (four or more within 350 km on a day, 8 or more in all) each had a daily PM2.5 mean of at least 25 µg/m³ and at least 2 times their usual for that time of year. Found in our own measurements, not picked by hand. How we find episodes. Values are each city's daily mean of its own monitors; causes are the usual kinds for a pattern like this, not a confirmed source.