SmogRank / Episodes / United States

North-western United States and Canada, 25 to 26 August 2026

For 2 days, from 25 to 26 August 2026, 9 cities in the United States and Canada had PM2.5 at least twice their usual for the time of year. The worst reading was Hope, British Columbia, Canada: 62.7 µg/m³ on 25 August, about 9.8× its usual 6.4. Ended 26 August.

Likely smoke from firesFires were detected within 300 km of the city on 100% of the counted city-days and smoke was mapped over the city on 75%. Satellites see crop, field and forest fires alike, so this doesn't say which burned.
Cities reached9in 2 countries
Days225 to 26 August 2026
Worst day25 August8 cities counted
Furthest above usual9.8×Hope

Day by day

25 August 8 cities at twice their usual or more
Moses LakeEphrataSunnysideGrandviewProsserTri-CitiesKennewickPascoToppenishYakimaFinleyEllensburgHermistonPendletonWalla WallaThe DallesCheneyLa GrandeAirway HeightsHood RiverNorth BendSpokanePullmanMeadUnion Hill-Novelty HillSpokane ValleyMonroeRedmondAuburnMoscowLiberty LakeKentRentonBellevueKirklandNorth CreekBothellColumbia CityBaker CityInglewood-Finn HillBurienWhite CenterSeattleMarysvilleParklandTacomaPicnic Point-North LynnwoodShorelineTulalipCoeur d'AleneRedmondBremertonGreshamMount VernonCastlegarLaceySalmon CreekBendVancouverRidgefieldNorth PortlandMilwaukiePortlandCentraliaOregon CityChehalisPort TownsendLongviewSandpointAnacortesBellinghamTigardCanbyBeavertonSheltonLyndenHillsboroWoodburnSilvertonWeiserForest GroveStaytonLangleyCrestonOntarioSalemMcMinnvilleSweet HomePort CoquitlamStrawberry HillCoquitlamPort AngelesVictoriaDeltaBurnabyAlbanyDallasCentral SaanichAberdeenLangfordRichmondNorth VancouverVancouverCorvallisWest VancouverEugeneDuncanNorth CowichanSquamishGibsonsCranbrookHarewoodNanaimoNewportFlorenceMissoulaColumbia FallsPort AlberniLewistonAbbotsfordQuincyPrinevilleMadrasAgassizChilliwackWenatcheeHope
22 Aug23242526272829
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

HopeHope, 22 August: 10.7 µg/m³Hope, 23 August: 2.4 µg/m³Hope, 24 August: 36.7 µg/m³Hope, 25 August: 62.7 µg/m³, 9.8× its usual 6.4Hope, 26 August: 10.5 µg/m³Hope, 27 August: 3.7 µg/m³Hope, 28 August: 2.0 µg/m³Hope, 29 August: 2.7 µg/m³ChilliwackChilliwack, 22 August: 8.1 µg/m³Chilliwack, 23 August: 2.4 µg/m³Chilliwack, 24 August: 13.3 µg/m³Chilliwack, 25 August: 46.0 µg/m³, 7.1× its usual 6.5Chilliwack, 26 August: 6.6 µg/m³Chilliwack, 27 August: 3.9 µg/m³Chilliwack, 28 August: 2.5 µg/m³Chilliwack, 29 August: 3.1 µg/m³AgassizAgassiz, 22 August: 8.1 µg/m³Agassiz, 23 August: 2.3 µg/m³Agassiz, 24 August: 21.7 µg/m³Agassiz, 25 August: 39.9 µg/m³, 6.0× its usual 6.7Agassiz, 26 August: 8.5 µg/m³Agassiz, 27 August: 3.9 µg/m³Agassiz, 28 August: 2.5 µg/m³Agassiz, 29 August: 3.2 µg/m³MadrasMadras, 22 August: 34.6 µg/m³Madras, 23 August: 8.9 µg/m³Madras, 24 August: 12.8 µg/m³Madras, 25 August: 38.5 µg/m³, 4.8× its usual 8.0Madras, 26 August: 38.9 µg/m³, 4.9× its usual 8.0Madras, 27 August: 51.1 µg/m³Madras, 28 August: 35.3 µg/m³Madras, 29 August: 18.6 µg/m³PrinevillePrineville, 22 August: 30.3 µg/m³Prineville, 23 August: 5.2 µg/m³Prineville, 24 August: 10.9 µg/m³Prineville, 25 August: 30.2 µg/m³, 4.4× its usual 6.9Prineville, 26 August: 31.5 µg/m³, 4.6× its usual 6.9Prineville, 27 August: 33.7 µg/m³Prineville, 28 August: 23.3 µg/m³Prineville, 29 August: 11.4 µg/m³WenatcheeWenatchee, 22 August: 38.5 µg/m³Wenatchee, 23 August: 5.9 µg/m³Wenatchee, 24 August: 26.1 µg/m³Wenatchee, 25 August: 28.3 µg/m³, 5.2× its usual 5.4Wenatchee, 26 August: 40.7 µg/m³, 7.5× its usual 5.4Wenatchee, 27 August: 16.8 µg/m³Wenatchee, 28 August: 12.3 µg/m³Wenatchee, 29 August: 12.6 µg/m³LewistonLewiston, 22 August: 19.6 µg/m³Lewiston, 23 August: 13.1 µg/m³Lewiston, 24 August: 10.6 µg/m³Lewiston, 25 August: 25.4 µg/m³, 2.6× its usual 9.6Lewiston, 26 August: 24.2 µg/m³Lewiston, 27 August: 12.6 µg/m³Lewiston, 28 August: 10.0 µg/m³Lewiston, 29 August: 5.4 µg/m³AbbotsfordAbbotsford, 22 August: 5.7 µg/m³Abbotsford, 23 August: 1.9 µg/m³Abbotsford, 24 August: 5.9 µg/m³Abbotsford, 25 August: 25.3 µg/m³, 4.1× its usual 6.2Abbotsford, 26 August: 4.7 µg/m³Abbotsford, 27 August: 3.0 µg/m³Abbotsford, 28 August: 2.6 µg/m³Abbotsford, 29 August: 3.4 µg/m³QuincyQuincy, 22 August: 16.4 µg/m³Quincy, 23 August: 7.3 µg/m³Quincy, 24 August: 20.8 µg/m³Quincy, 25 August: 9.3 µg/m³Quincy, 26 August: 29.5 µg/m³, 4.5× its usual 6.5Quincy, 27 August: 14.5 µg/m³Quincy, 28 August: 9.9 µg/m³Quincy, 29 August: 8.9 µg/m³22 Aug23242526272829
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
HopeBritish Columbia, Canada1 62.725 August6.49.8×
WenatcheeWashington, United States2 40.726 August5.47.5×
ChilliwackBritish Columbia, Canada1 46.025 August6.57.1×
AgassizBritish Columbia, Canada1 39.925 August6.76.0×
MadrasOregon, United States2 38.926 August8.04.9×
PrinevilleOregon, United States2 31.526 August6.94.6×
QuincyWashington, United States1 29.526 August6.54.5×
AbbotsfordBritish Columbia, Canada1 25.325 August6.24.1×
LewistonIdaho, United States1 25.425 August9.62.6×

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 145 of 173 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 173.

Use this page

SmogRank, North-western United States and Canada, 25 to 26 August 2026: 9 cities with PM2.5 at twice their usual or more, 25 to 26 August 2026, smogrank.com/episodes/2026-08-25-north-western-united-states-and-canada (accessed 5 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. Fire detections from NASA FIRMS; smoke maps from NOAA HMS.