SmogRank / Episodes / United States
United States and Canada, June 2023
For 6 days, from 14 to 19 June 2023, 195 cities in the United States and Canada had PM2.5 at least twice their usual for the time of year. The worst reading was Saint Paul, Minnesota, United States: 105.0 µg/m³ on 14 June, about 17× its usual 6.3. Ended 19 June.
Day by day
How it spread
Every city it reached
| City | Days | Highest | Above usual |
|---|---|---|---|
| Saint CloudMinnesota, United States | 3 | 99.514 June | 18× |
| Saint MichaelMinnesota, United States | 3 | 100.014 June | 17× |
| Saint PaulMinnesota, United States | 2 | 105.014 June | 17× |
| MinneapolisMinnesota, United States | 3 | 105.014 June | 15× |
| BurnsvilleMinnesota, United States | 3 | 95.514 June | 15× |
| BrainerdMinnesota, United States | 1 | 75.814 June | 15× |
| BlaineMinnesota, United States | 2 | 84.814 June | 15× |
| ShakopeeMinnesota, United States | 2 | 89.014 June | 15× |
| Apple ValleyMinnesota, United States | 2 | 84.514 June | 14× |
| Detroit LakesMinnesota, United States | 1 | 83.014 June | 14× |
| CloquetMinnesota, United States | 1 | 63.914 June | 13× |
| West FargoNorth Dakota, United States | 1 | 75.414 June | 12× |
| DuluthMinnesota, United States | 1 | 62.214 June | 11× |
| VirginiaMinnesota, United States | 1 | 57.814 June | 10× |
| AltoonaWisconsin, United States | 1 | 55.914 June | 9.8× |
| Eau ClaireWisconsin, United States | 1 | 55.914 June | 9.8× |
| MarshallMinnesota, United States | 1 | 47.415 June | 9.5× |
| North BayOntario, Canada | 3 | 60.418 June | 9.3× |
| SuperiorWisconsin, United States | 1 | 58.914 June | 8.7× |
| BellevilleOntario, Canada | 2 | 50.517 June | 8.6× |
| MolineIllinois, United States | 2 | 49.915 June | 8.2× |
| ClintonIowa, United States | 4 | 56.015 June | 8.0× |
| AberdeenSouth Dakota, United States | 1 | 39.915 June | 8.0× |
| RochesterMinnesota, United States | 2 | 55.515 June | 7.9× |
| BarabooWisconsin, United States | 5 | 38.114 June | 7.6× |
| DavenportIowa, United States | 2 | 49.015 June | 7.3× |
| Iowa CityIowa, United States | 1 | 46.315 June | 7.2× |
| OttawaOntario, Canada | 1 | 44.516 June | 7.2× |
| MadisonWisconsin, United States | 5 | 40.314 June | 6.9× |
| WaterlooIowa, United States | 1 | 51.315 June | 6.8× |
| MurraysvilleNorth Carolina, United States | 1 | 41.416 June | 6.6× |
| AppletonWisconsin, United States | 4 | 40.217 June | 6.5× |
| Green BayWisconsin, United States | 2 | 40.617 June | 6.4× |
| WatertownSouth Dakota, United States | 1 | 36.615 June | 6.2× |
| Rouyn-NorandaQuebec, Canada | 2 | 39.018 June | 5.9× |
| Parry SoundOntario, Canada | 2 | 36.316 June | 5.8× |
| CornwallOntario, Canada | 1 | 35.016 June | 5.6× |
| JeffersontownKentucky, United States | 4 | 39.315 June | 5.5× |
| JeffersonvilleIndiana, United States | 4 | 43.815 June | 5.3× |
| TecumsehMichigan, United States | 2 | 40.116 June | 5.3× |
| Saint MatthewsKentucky, United States | 4 | 39.515 June | 5.3× |
| DublinOhio, United States | 3 | 40.217 June | 5.2× |
| TaylorMichigan, United States | 2 | 36.917 June | 5.1× |
| MuscatineIowa, United States | 1 | 34.015 June | 5.0× |
| ChathamOntario, Canada | 2 | 31.717 June | 5.0× |
| ConwaySouth Carolina, United States | 2 | 30.218 June | 5.0× |
| Red HillSouth Carolina, United States | 2 | 30.218 June | 5.0× |
| LouisvilleKentucky, United States | 3 | 39.815 June | 4.9× |
| ElizabethtownKentucky, United States | 3 | 36.618 June | 4.9× |
| RockfordIllinois, United States | 4 | 36.315 June | 4.9× |
| MontréalQuebec, Canada | 1 | 34.916 June | 4.9× |
| Warrensville HeightsOhio, United States | 1 | 34.217 June | 4.9× |
| PeterboroughOntario, Canada | 3 | 31.718 June | 4.9× |
| Saint-Jean-sur-RichelieuQuebec, Canada | 1 | 26.116 June | 4.9× |
| WindsorOntario, Canada | 3 | 40.017 June | 4.8× |
| Lincoln ParkMichigan, United States | 2 | 39.617 June | 4.8× |
| AkronOhio, United States | 2 | 37.117 June | 4.8× |
| WaukeshaWisconsin, United States | 3 | 33.817 June | 4.8× |
| YpsilantiMichigan, United States | 2 | 34.817 June | 4.7× |
| BloomingtonIndiana, United States | 3 | 29.815 June | 4.7× |
| GahannaOhio, United States | 1 | 28.617 June | 4.7× |
| New AlbanyOhio, United States | 1 | 28.617 June | 4.7× |
| DetroitMichigan, United States | 2 | 40.317 June | 4.6× |
| MedinaOhio, United States | 2 | 34.317 June | 4.6× |
| Fort ThomasKentucky, United States | 2 | 31.517 June | 4.6× |
| Highland HeightsKentucky, United States | 2 | 31.517 June | 4.6× |
| Rivière-des-Prairies–Pointe-aux-TremblesQuebec, Canada | 1 | 28.416 June | 4.6× |
| AndersonIndiana, United States | 3 | 32.618 June | 4.5× |
| St. ThomasOntario, Canada | 3 | 32.116 June | 4.5× |
| New BaltimoreMichigan, United States | 2 | 31.916 June | 4.5× |
| DorvalQuebec, Canada | 1 | 30.316 June | 4.5× |
| GranbyQuebec, Canada | 1 | 29.116 June | 4.5× |
| PikevilleKentucky, United States | 2 | 27.217 June | 4.5× |
| St. CatharinesOntario, Canada | 3 | 31.618 June | 4.4× |
| New BrightonPennsylvania, United States | 1 | 31.117 June | 4.4× |
| Weirton HeightsWest Virginia, United States | 1 | 30.617 June | 4.4× |
| GreendaleWisconsin, United States | 3 | 30.118 June | 4.4× |
| South MilwaukeeWisconsin, United States | 3 | 30.118 June | 4.4× |
| EriePennsylvania, United States | 2 | 29.717 June | 4.4× |
| HazardKentucky, United States | 3 | 29.216 June | 4.4× |
| DearbornMichigan, United States | 2 | 38.717 June | 4.3× |
| South BendIndiana, United States | 2 | 38.218 June | 4.3× |
| MonessenPennsylvania, United States | 3 | 37.717 June | 4.3× |
| SarniaOntario, Canada | 3 | 32.519 June | 4.3× |
| BloomingtonIllinois, United States | 5 | 27.718 June | 4.3× |
| ClevelandOhio, United States | 4 | 40.417 June | 4.2× |
| East ChicagoIndiana, United States | 1 | 31.418 June | 4.2× |
| RoanokeVirginia, United States | 2 | 30.816 June | 4.2× |
| BraidwoodIllinois, United States | 2 | 29.618 June | 4.2× |
| Port HuronMichigan, United States | 2 | 29.516 June | 4.2× |
| BrossardQuebec, Canada | 1 | 29.316 June | 4.2× |
| State CollegePennsylvania, United States | 1 | 26.717 June | 4.2× |
| Valley StationKentucky, United States | 3 | 34.015 June | 4.1× |
| HermitagePennsylvania, United States | 1 | 28.517 June | 4.1× |
| CantonOhio, United States | 3 | 38.217 June | 4.0× |
| Beaver FallsPennsylvania, United States | 2 | 36.617 June | 4.0× |
| FlatwoodsKentucky, United States | 4 | 35.517 June | 4.0× |
| BuffaloNew York, United States | 2 | 32.117 June | 4.0× |
| Columbia CityIndiana, United States | 2 | 31.818 June | 4.0× |
| LondonOntario, Canada | 3 | 29.916 June | 4.0× |
| AshlandKentucky, United States | 3 | 29.817 June | 4.0× |
| MasonOhio, United States | 2 | 29.317 June | 4.0× |
| SharonvilleOhio, United States | 2 | 29.317 June | 4.0× |
| JohnstownPennsylvania, United States | 1 | 27.917 June | 4.0× |
| Lexington-FayetteKentucky, United States | 1 | 26.518 June | 4.0× |
| IndianapolisIndiana, United States | 3 | 38.918 June | 3.9× |
| NapervilleIllinois, United States | 4 | 34.817 June | 3.9× |
| WilkinsburgPennsylvania, United States | 1 | 33.317 June | 3.9× |
| MilwaukeeWisconsin, United States | 3 | 32.518 June | 3.9× |
| YoungstownOhio, United States | 1 | 31.617 June | 3.9× |
| KitchenerOntario, Canada | 1 | 30.216 June | 3.9× |
| LebanonOhio, United States | 2 | 28.418 June | 3.9× |
| New AlbanyIndiana, United States | 2 | 28.318 June | 3.9× |
| PittsburghPennsylvania, United States | 1 | 34.717 June | 3.8× |
| Kennedy TownshipPennsylvania, United States | 1 | 34.517 June | 3.8× |
| SpringfieldOhio, United States | 3 | 34.218 June | 3.8× |
| DaytonOhio, United States | 3 | 33.418 June | 3.8× |
| MoundsvilleWest Virginia, United States | 3 | 33.217 June | 3.8× |
| Calumet CityIllinois, United States | 3 | 31.617 June | 3.8× |
| Jefferson HillsPennsylvania, United States | 1 | 31.517 June | 3.8× |
| McKeesportPennsylvania, United States | 1 | 31.517 June | 3.8× |
| CaryIllinois, United States | 3 | 31.017 June | 3.8× |
| Des PlainesIllinois, United States | 2 | 31.017 June | 3.8× |
| MiddlesboroKentucky, United States | 2 | 28.918 June | 3.8× |
| AltoonaPennsylvania, United States | 2 | 26.817 June | 3.8× |
| WarrenOhio, United States | 1 | 33.317 June | 3.7× |
| GreenvilleSouth Carolina, United States | 2 | 29.317 June | 3.7× |
| ClaymontDelaware, United States | 1 | 26.018 June | 3.7× |
| ChesterPennsylvania, United States | 1 | 26.018 June | 3.7× |
| RedfordMichigan, United States | 2 | 36.117 June | 3.6× |
| JolietIllinois, United States | 4 | 32.117 June | 3.6× |
| CharlottesvilleVirginia, United States | 1 | 26.518 June | 3.6× |
| SavoyIllinois, United States | 1 | 25.118 June | 3.6× |
| NorwoodOhio, United States | 2 | 32.817 June | 3.5× |
| CincinnatiOhio, United States | 2 | 32.118 June | 3.5× |
| HammondIndiana, United States | 3 | 30.817 June | 3.5× |
| ScrantonPennsylvania, United States | 1 | 27.117 June | 3.5× |
| DentsvilleSouth Carolina, United States | 1 | 26.618 June | 3.5× |
| Rose HillVirginia, United States | 2 | 26.517 June | 3.5× |
| MiddletownOhio, United States | 2 | 35.517 June | 3.4× |
| SpartanburgSouth Carolina, United States | 2 | 33.517 June | 3.4× |
| SteubenvilleOhio, United States | 1 | 32.917 June | 3.4× |
| PortageIndiana, United States | 1 | 28.818 June | 3.4× |
| BensalemPennsylvania, United States | 1 | 28.318 June | 3.4× |
| BrantfordOntario, Canada | 2 | 28.116 June | 3.4× |
| BarrieOntario, Canada | 1 | 27.216 June | 3.4× |
| LansingMichigan, United States | 1 | 27.016 June | 3.4× |
| LancasterPennsylvania, United States | 2 | 26.819 June | 3.4× |
| RichmondVirginia, United States | 2 | 26.518 June | 3.4× |
| KingsportTennessee, United States | 1 | 25.718 June | 3.4× |
| PoquosonVirginia, United States | 1 | 25.118 June | 3.4× |
| KokomoIndiana, United States | 1 | 25.118 June | 3.4× |
| ToledoOhio, United States | 1 | 28.317 June | 3.3× |
| NorthbrookIllinois, United States | 1 | 27.518 June | 3.3× |
| HudsonvilleMichigan, United States | 1 | 25.917 June | 3.3× |
| JenisonMichigan, United States | 1 | 25.917 June | 3.3× |
| La CrosseWisconsin, United States | 3 | 35.115 June | 3.2× |
| GainesvilleGeorgia, United States | 1 | 31.518 June | 3.2× |
| FlorenceSouth Carolina, United States | 2 | 29.117 June | 3.2× |
| KnoxvilleTennessee, United States | 1 | 27.518 June | 3.2× |
| ClaytonNorth Carolina, United States | 2 | 27.417 June | 3.2× |
| KenmoreNew York, United States | 1 | 27.418 June | 3.2× |
| DecaturIllinois, United States | 2 | 26.918 June | 3.2× |
| FlintMichigan, United States | 2 | 26.816 June | 3.2× |
| RaleighNorth Carolina, United States | 2 | 26.818 June | 3.2× |
| LafayetteIndiana, United States | 1 | 26.618 June | 3.2× |
| GreenvilleNorth Carolina, United States | 1 | 25.518 June | 3.2× |
| ElkhartIndiana, United States | 1 | 30.818 June | 3.1× |
| Saint AndrewsSouth Carolina, United States | 1 | 29.218 June | 3.1× |
| Winston-SalemNorth Carolina, United States | 2 | 27.418 June | 3.1× |
| TorontoOntario, Canada | 1 | 26.318 June | 3.1× |
| ClemmonsNorth Carolina, United States | 1 | 26.218 June | 3.1× |
| West MifflinPennsylvania, United States | 2 | 33.718 June | 3.0× |
| LimaOhio, United States | 1 | 32.017 June | 3.0× |
| PhiladelphiaPennsylvania, United States | 1 | 28.118 June | 3.0× |
| LawrencevilleGeorgia, United States | 1 | 26.718 June | 3.0× |
| PennsaukenNew Jersey, United States | 1 | 25.918 June | 3.0× |
| New HollandPennsylvania, United States | 1 | 25.118 June | 3.0× |
| Terre HauteIndiana, United States | 2 | 32.218 June | 2.9× |
| Franklin ParkIllinois, United States | 2 | 27.217 June | 2.9× |
| Grand RapidsMichigan, United States | 1 | 26.517 June | 2.9× |
| New York CityNew York, United States | 1 | 26.117 June | 2.9× |
| EvansvilleIndiana, United States | 1 | 25.918 June | 2.9× |
| ChicagoIllinois, United States | 1 | 25.918 June | 2.8× |
| Roanoke RapidsNorth Carolina, United States | 1 | 25.819 June | 2.8× |
| Granite CityIllinois, United States | 1 | 25.316 June | 2.8× |
| GreensboroNorth Carolina, United States | 1 | 25.018 June | 2.8× |
| HarrisburgPennsylvania, United States | 1 | 25.019 June | 2.8× |
| FairviewGeorgia, United States | 2 | 27.718 June | 2.7× |
| East RidgeTennessee, United States | 2 | 27.718 June | 2.7× |
| ChattanoogaTennessee, United States | 2 | 26.117 June | 2.7× |
| OwensboroKentucky, United States | 2 | 26.716 June | 2.6× |
| GaryIndiana, United States | 1 | 25.418 June | 2.6× |
| Candler-McAfeeGeorgia, United States | 1 | 25.118 June | 2.6× |
| CheektowagaNew York, United States | 2 | 34.418 June | 2.1× |
Daily means in µg/m³, over the days each city counted in this episode. Highest: its highest of those days. Usual: the city's median for the time of year of that day (its days within 21 days of the date, every year, leaving out the week around it). Above usual: its highest day against that, with a usual under 5 µg/m³ taken as 5.
Against other episodes in the United States and Canada
Number 7 of 173 episodes in the United States and Canada since our records began, by cities reached.
- Eastern United States and Canada, June and July 2023343
- Northern United States and Canada, July 2026327
- United States and Canada, July 2023322
- Eastern United States and Canada, May and June 2023317
- North-eastern United States and Canada, 29 July to 9 August 2025292
- Northern United States and Canada, May and June 2025247
- United States and Canada, June 2023195
- North-western United States and Canada, August 2023176
- North-western United States and Canada, 4 to 22 August 2026151
- Northern United States and Canada, July 2025139
- Northern United States and Canada, June 2025134
- North-western United States and Canada, July and August 2026118
Bars: cities reached; colour: the level of the episode's highest daily reading. All 173.
Use this page
SmogRank, United States and Canada, June 2023: 195 cities with PM2.5 at twice their usual or more, 14 to 19 June 2023, smogrank.com/episodes/2023-06-united-states-and-canada (accessed 5 October 2026).
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. Fire detections from NASA FIRMS; smoke maps from NOAA HMS.