SmogRank / Episodes / United States

Minnesota, United States, August 2023

For 1 day, on 18 August 2023, 9 cities in the United States had PM2.5 at least twice their usual for the time of year. The worst reading was Minneapolis, Minnesota, United States: 37.9 µg/m³ on 18 August, about 4.0× its usual 9.5.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached9in 1 country
Days118 August 2023
Worst day18 August9 cities counted
Furthest above usual4.2×Brookings

Day by day

18 August 9 cities at twice their usual or more
BlaineSaint PaulRochesterWatertownWest FargoSioux FallsEau ClaireLa CrosseAberdeenShakopeeBurnsvilleSuperiorApple ValleySaint MichaelSaint CloudDuluthMinneapolisBrookings
15 Aug161718192021
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

BrookingsBrookings, 15 August: 31.0 µg/m³, 4.9× usualBrookings, 16 August: 7.7 µg/m³, 1.2× usualBrookings, 17 August: 25.5 µg/m³, 4.0× usualBrookings, 18 August: 26.7 µg/m³, 4.2× usualBrookings, 19 August: 12.1 µg/m³, 1.9× usualBrookings, 20 August: 10.9 µg/m³, 1.7× usualBrookings, 21 August: 12.4 µg/m³, 2.0× usualMinneapolisMinneapolis, 15 August: 6.0 µg/m³, 0.6× usualMinneapolis, 16 August: 6.4 µg/m³, 0.7× usualMinneapolis, 17 August: 16.0 µg/m³, 1.7× usualMinneapolis, 18 August: 37.9 µg/m³, 4.0× usualMinneapolis, 19 August: 13.2 µg/m³, 1.4× usualMinneapolis, 20 August: 18.8 µg/m³, 2.0× usualMinneapolis, 21 August: 18.3 µg/m³, 1.9× usualDuluthDuluth, 15 August: 6.2 µg/m³, 0.8× usualDuluth, 16 August: 6.8 µg/m³, 0.9× usualDuluth, 17 August: 22.8 µg/m³, 2.9× usualDuluth, 18 August: 28.4 µg/m³, 3.6× usualDuluth, 19 August: 16.7 µg/m³, 2.1× usualDuluth, 20 August: 16.2 µg/m³, 2.1× usualDuluth, 21 August: 9.1 µg/m³, 1.2× usualSaint CloudSaint Cloud, 15 August: 5.4 µg/m³, 0.7× usualSaint Cloud, 16 August: 7.2 µg/m³, 0.9× usualSaint Cloud, 17 August: 19.6 µg/m³, 2.4× usualSaint Cloud, 18 August: 28.3 µg/m³, 3.4× usualSaint Cloud, 19 August: 16.6 µg/m³, 2.0× usualSaint Cloud, 20 August: 20.2 µg/m³, 2.4× usualSaint Cloud, 21 August: 17.9 µg/m³, 2.2× usualBurnsvilleBurnsville, 15 August: 6.0 µg/m³, 0.6× usualBurnsville, 16 August: 6.8 µg/m³, 0.7× usualBurnsville, 17 August: 16.1 µg/m³, 1.6× usualBurnsville, 18 August: 27.3 µg/m³, 2.8× usualBurnsville, 19 August: 14.7 µg/m³, 1.5× usualBurnsville, 20 August: 21.0 µg/m³, 2.1× usualBurnsville, 21 August: 20.8 µg/m³, 2.1× usualShakopeeShakopee, 15 August: 4.9 µg/m³, 0.5× usualShakopee, 16 August: 6.9 µg/m³, 0.7× usualShakopee, 17 August: 16.1 µg/m³, 1.7× usualShakopee, 18 August: 26.9 µg/m³, 2.8× usualShakopee, 19 August: 14.6 µg/m³, 1.5× usualShakopee, 20 August: 20.4 µg/m³, 2.1× usualShakopee, 21 August: 21.1 µg/m³, 2.2× usualSaint MichaelSaint Michael, 15 August: 4.2 µg/m³, 0.5× usualSaint Michael, 16 August: 6.8 µg/m³, 0.8× usualSaint Michael, 17 August: 16.4 µg/m³, 2.0× usualSaint Michael, 18 August: 26.6 µg/m³, 3.2× usualSaint Michael, 19 August: 14.2 µg/m³, 1.7× usualSaint Michael, 20 August: 18.3 µg/m³, 2.2× usualSaint Michael, 21 August: 19.6 µg/m³, 2.3× usualSuperiorSuperior, 15 August: 7.3 µg/m³, 0.8× usualSuperior, 16 August: 6.3 µg/m³, 0.7× usualSuperior, 17 August: 21.7 µg/m³, 2.5× usualSuperior, 18 August: 26.5 µg/m³, 3.0× usualSuperior, 19 August: 16.3 µg/m³, 1.9× usualSuperior, 20 August: 15.4 µg/m³, 1.8× usualSuperior, 21 August: 8.5 µg/m³, 1.0× usualApple ValleyApple Valley, 15 August: 4.8 µg/m³, 0.6× usualApple Valley, 16 August: 6.1 µg/m³, 0.8× usualApple Valley, 17 August: 14.8 µg/m³, 1.8× usualApple Valley, 18 August: 25.3 µg/m³, 3.1× usualApple Valley, 19 August: 12.1 µg/m³, 1.5× usualApple Valley, 20 August: 19.1 µg/m³, 2.4× usualApple Valley, 21 August: 18.8 µg/m³, 2.3× usual15 Aug161718192021
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
BrookingsSouth Dakota, United States1 31.015 August6.34.9×
MinneapolisMinnesota, United States1 37.918 August9.54.0×
DuluthMinnesota, United States1 28.418 August7.93.6×
Saint CloudMinnesota, United States1 28.318 August8.33.4×
Saint MichaelMinnesota, United States1 26.618 August8.43.2×
Apple ValleyMinnesota, United States1 25.318 August8.13.1×
SuperiorWisconsin, United States1 26.518 August8.73.0×
ShakopeeMinnesota, United States1 26.918 August9.62.8×
BurnsvilleMinnesota, United States1 27.318 August9.92.8×

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

Number 34 of 41 episodes in the United States since our records began, by cities reached.

Bars: cities reached; colour: the level of the episode's highest daily reading. All 41.

Use this page

SmogRank, Minnesota, United States, August 2023: 9 cities with PM2.5 at twice their usual or more, 18 August 2023, smogrank.com/episodes/2023-08-minnesota-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.