SmogRank / Episodes / United States

Washington and Oregon, United States, July 2026

For 2 days, from 16 to 17 July 2026, 8 cities in the United States had PM2.5 at least twice their usual for the time of year. The worst reading was Spokane Valley, Washington, United States: 123.0 µg/m³ on 17 July, about 19× its usual 6.6.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached8in 1 country
Days216 to 17 July 2026
Worst day17 July5 cities counted
Furthest above usual19×Spokane Valley

Day by day

17 July 5 cities at twice their usual or more
LewistonTri-CitiesMoses LakeSunnysideWenatcheeYakimaEllensburgThe DallesRedmondMissoulaMonroeUnion Hill-Novelty HillRedmondAuburnKentRentonBellevueKirklandNorth CreekBothellColumbia CityBurienSeattlePicnic Point-North LynnwoodParklandShorelineTacomaGreshamMount VernonBremertonSalmon CreekVancouverOregon CityMilwaukiePortlandLaceyAbbotsfordCanbyTigardBeavertonBellinghamCentraliaLongviewAnacortesWoodburnHillsboroForest GroveLangleySalemMcMinnvilleAlbanyDeltaCorvallisPullmanPendletonMoscowHermistonWalla WallaSpokaneCoeur d'AleneSpokane Valley
13 Jul14151617181920
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

Walla WallaWalla Walla, 13 July: 3.6 µg/m³, 0.7× usualWalla Walla, 14 July: 5.8 µg/m³, 1.1× usualWalla Walla, 15 July: 8.5 µg/m³, 1.5× usualWalla Walla, 16 July: 37.8 µg/m³, 6.9× usualWalla Walla, 17 July: 14.4 µg/m³, 2.6× usualWalla Walla, 18 July: 7.2 µg/m³, 1.3× usualWalla Walla, 19 July: 6.6 µg/m³, 1.2× usualWalla Walla, 20 July: 24.9 µg/m³, 4.5× usualSpokane ValleySpokane Valley, 13 July: 4.7 µg/m³, 0.7× usualSpokane Valley, 14 July: 5.5 µg/m³, 0.8× usualSpokane Valley, 15 July: 4.8 µg/m³, 0.7× usualSpokane Valley, 16 July: 27.8 µg/m³, 4.2× usualSpokane Valley, 17 July: 123.0 µg/m³, 19× usualSpokane Valley, 18 July: 14.9 µg/m³, 2.3× usualSpokane Valley, 19 July: 11.7 µg/m³, 1.8× usualSpokane Valley, 20 July: 22.6 µg/m³, 3.4× usualHermistonHermiston, 13 July: 3.8 µg/m³, 0.7× usualHermiston, 14 July: 6.7 µg/m³, 1.2× usualHermiston, 15 July: 7.1 µg/m³, 1.3× usualHermiston, 16 July: 27.8 µg/m³, 5.1× usualHermiston, 17 July: 15.0 µg/m³, 2.8× usualHermiston, 18 July: 5.4 µg/m³, 1.0× usualHermiston, 19 July: 5.2 µg/m³, 1.0× usualHermiston, 20 July: 18.7 µg/m³, 3.5× usualPendletonPendleton, 13 July: 3.4 µg/m³, 0.6× usualPendleton, 14 July: 6.8 µg/m³, 1.2× usualPendleton, 15 July: 8.0 µg/m³, 1.5× usualPendleton, 16 July: 26.8 µg/m³, 4.9× usualPendleton, 17 July: 18.8 µg/m³, 3.4× usualPendleton, 18 July: 9.0 µg/m³, 1.6× usualPendleton, 19 July: 8.7 µg/m³, 1.6× usualPendleton, 20 July: 62.4 µg/m³, 11× usualSpokaneSpokane, 13 July: 5.4 µg/m³, 0.8× usualSpokane, 14 July: 5.7 µg/m³, 0.9× usualSpokane, 15 July: 5.9 µg/m³, 0.9× usualSpokane, 16 July: 13.9 µg/m³, 2.1× usualSpokane, 17 July: 98.1 µg/m³, 15× usualSpokane, 18 July: 11.7 µg/m³, 1.7× usualSpokane, 19 July: 20.9 µg/m³, 3.1× usualSpokane, 20 July: 31.5 µg/m³, 4.7× usualCoeur d'AleneCoeur d'Alene, 13 July: no readingCoeur d'Alene, 14 July: no readingCoeur d'Alene, 15 July: no readingCoeur d'Alene, 16 July: no readingCoeur d'Alene, 17 July: 97.8 µg/m³, 15× usualCoeur d'Alene, 18 July: 16.5 µg/m³, 2.5× usualCoeur d'Alene, 19 July: 6.1 µg/m³, 0.9× usualCoeur d'Alene, 20 July: 16.2 µg/m³, 2.5× usualMoscowMoscow, 13 July: 2.5 µg/m³, 0.4× usualMoscow, 14 July: 3.3 µg/m³, 0.5× usualMoscow, 15 July: 5.7 µg/m³, 0.8× usualMoscow, 16 July: 5.1 µg/m³, 0.7× usualMoscow, 17 July: 35.4 µg/m³, 5.1× usualMoscow, 18 July: 15.9 µg/m³, 2.3× usualMoscow, 19 July: 3.0 µg/m³, 0.4× usualMoscow, 20 July: 7.5 µg/m³, 1.1× usualPullmanPullman, 13 July: 4.0 µg/m³, 0.7× usualPullman, 14 July: 5.3 µg/m³, 0.9× usualPullman, 15 July: 5.7 µg/m³, 1.0× usualPullman, 16 July: 7.9 µg/m³, 1.4× usualPullman, 17 July: 26.4 µg/m³, 4.6× usualPullman, 18 July: 10.2 µg/m³, 1.8× usualPullman, 19 July: 5.3 µg/m³, 0.9× usualPullman, 20 July: 9.0 µg/m³, 1.6× usual13 Jul14151617181920
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
Spokane ValleyWashington, United States2 123.017 July6.619×
Coeur d'AleneIdaho, United States1 97.817 July6.515×
SpokaneWashington, United States1 98.117 July6.715×
PendletonOregon, United States1 62.420 July5.511×
Walla WallaWashington, United States1 37.816 July5.56.9×
HermistonOregon, United States1 27.816 July5.45.1×
MoscowIdaho, United States1 35.417 July7.05.1×
PullmanWashington, United States1 26.417 July5.74.6×

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

Number 86 of 98 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 98.

Use this page

SmogRank, Washington and Oregon, United States, July 2026: 8 cities with PM2.5 at twice their usual or more, 16 to 17 July 2026, smogrank.com/episodes/2026-07-washington-and-oregon-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.