SmogRank / Episodes / United States
North-western United States and Canada, August 2026
For 7 days, from 10 to 16 August 2026, 31 cities in the United States and Canada had PM2.5 at least twice their usual for the time of year. The worst reading was Vernon, British Columbia, Canada: 142.0 µg/m³ on 10 August, about 16× its usual 9.1.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 31 in 2 countries
Days 7 10 to 16 August 2026
Worst day 10 August 14 cities counted
Furthest above usual 20× Wenatchee
Day by day
Play 10 August 14 cities at twice their usual or more
Coeur d'Alene Moscow Pullman Calgary Airdrie Medicine Hat Boise Meridian Idaho Falls Hermiston Pocatello Swift Current Monroe Union Hill-Novelty Hill Redmond North Creek Marysville Bellevue Bothell Kirkland Renton Inglewood-Finn Hill Auburn Kent Columbia City Picnic Point-North Lynnwood Abbotsford Seattle Shoreline Mount Vernon Burien Parkland Tacoma Bellingham Anacortes Bremerton Langley Gresham Lacey Port Coquitlam Coquitlam Salmon Creek Vancouver Strawberry Hill Oregon City Milwaukie Portland Centralia Burnaby Canby Longview Tigard Delta Beaverton North Vancouver Vancouver Richmond West Vancouver Woodburn Saskatoon Hillsboro Squamish Forest Grove Salem Albany Eugene Casper Redmond Red Deer Bend Nampa Lewiston Great Falls Helena Lethbridge Kennewick Spokane Valley Pendleton Spokane Butte Walla Walla Sunnyside Sheridan Billings Tri-Cities The Dalles Pasco Moses Lake Chilliwack Missoula Bozeman Cranbrook Yakima Kamloops Ellensburg Kelowna Vernon Wenatchee 7 Aug 8 9 10 11 12 13 14 15 16 17 18 19 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
Kamloops Kamloops, 7 August: 191.0 µg/m³, 17× usual Kamloops, 8 August: 140.0 µg/m³, 13× usual Kamloops, 9 August: 167.0 µg/m³, 15× usual Kamloops, 10 August: 97.5 µg/m³, 8.7× usual Kamloops, 11 August: 18.4 µg/m³, 1.6× usual Kamloops, 12 August: 8.0 µg/m³, 0.7× usual Kamloops, 13 August: 9.3 µg/m³, 0.8× usual Kamloops, 14 August: 19.3 µg/m³, 1.7× usual Kamloops, 15 August: 43.0 µg/m³, 3.8× usual Kamloops, 16 August: 23.6 µg/m³, 2.1× usual Kamloops, 17 August: 27.5 µg/m³, 2.5× usual Kamloops, 18 August: 33.2 µg/m³, 3.0× usual Kamloops, 19 August: 29.6 µg/m³, 2.6× usual Vernon Vernon, 7 August: 102.0 µg/m³, 11× usual Vernon, 8 August: 71.8 µg/m³, 7.9× usual Vernon, 9 August: 102.0 µg/m³, 11× usual Vernon, 10 August: 142.0 µg/m³, 16× usual Vernon, 11 August: 118.0 µg/m³, 13× usual Vernon, 12 August: 7.5 µg/m³, 0.8× usual Vernon, 13 August: 9.3 µg/m³, 1.0× usual Vernon, 14 August: 8.7 µg/m³, 1.0× usual Vernon, 15 August: 22.6 µg/m³, 2.5× usual Vernon, 16 August: 39.3 µg/m³, 4.3× usual Vernon, 17 August: 23.4 µg/m³, 2.6× usual Vernon, 18 August: 17.9 µg/m³, 2.0× usual Vernon, 19 August: 20.2 µg/m³, 2.2× usual Wenatchee Wenatchee, 7 August: 99.9 µg/m³, 20× usual Wenatchee, 8 August: 8.6 µg/m³, 1.7× usual Wenatchee, 9 August: 14.0 µg/m³, 2.8× usual Wenatchee, 10 August: 5.2 µg/m³, 1.0× usual Wenatchee, 11 August: 6.1 µg/m³, 1.2× usual Wenatchee, 12 August: 38.7 µg/m³, 7.7× usual Wenatchee, 13 August: 57.5 µg/m³, 12× usual Wenatchee, 14 August: 35.2 µg/m³, 7.0× usual Wenatchee, 15 August: 97.8 µg/m³, 20× usual Wenatchee, 16 August: 76.5 µg/m³, 15× usual Wenatchee, 17 August: 45.9 µg/m³, 9.2× usual Wenatchee, 18 August: 17.1 µg/m³, 3.4× usual Wenatchee, 19 August: 16.9 µg/m³, 3.4× usual Cranbrook Cranbrook, 7 August: 84.2 µg/m³, 9.5× usual Cranbrook, 8 August: 63.8 µg/m³, 7.2× usual Cranbrook, 9 August: 93.4 µg/m³, 10× usual Cranbrook, 10 August: 68.4 µg/m³, 7.7× usual Cranbrook, 11 August: 58.5 µg/m³, 6.6× usual Cranbrook, 12 August: 29.2 µg/m³, 3.3× usual Cranbrook, 13 August: 8.2 µg/m³, 0.9× usual Cranbrook, 14 August: 2.3 µg/m³, 0.3× usual Cranbrook, 15 August: 8.7 µg/m³, 1.0× usual Cranbrook, 16 August: 15.5 µg/m³, 1.7× usual Cranbrook, 17 August: 18.1 µg/m³, 2.0× usual Cranbrook, 18 August: 34.5 µg/m³, 3.9× usual Cranbrook, 19 August: 38.5 µg/m³, 4.3× usual Nampa Nampa, 7 August: 77.5 µg/m³, 7.8× usual Nampa, 8 August: 70.8 µg/m³, 7.1× usual Nampa, 9 August: 35.7 µg/m³, 3.6× usual Nampa, 10 August: 34.3 µg/m³, 3.4× usual Nampa, 11 August: 39.4 µg/m³, 3.9× usual Nampa, 12 August: 24.3 µg/m³, 2.4× usual Nampa, 13 August: 26.3 µg/m³, 2.6× usual Nampa, 14 August: 14.1 µg/m³, 1.4× usual Nampa, 15 August: 8.4 µg/m³, 0.8× usual Nampa, 16 August: 3.5 µg/m³, 0.4× usual Nampa, 17 August: 8.7 µg/m³, 0.9× usual Nampa, 18 August: 13.6 µg/m³, 1.4× usual Nampa, 19 August: 16.4 µg/m³, 1.6× usual Kelowna Kelowna, 7 August: 59.8 µg/m³, 7.1× usual Kelowna, 8 August: 20.2 µg/m³, 2.4× usual Kelowna, 9 August: 40.8 µg/m³, 4.9× usual Kelowna, 10 August: no reading Kelowna, 11 August: 94.3 µg/m³, 11× usual Kelowna, 12 August: 15.3 µg/m³, 1.8× usual Kelowna, 13 August: 16.3 µg/m³, 1.9× usual Kelowna, 14 August: 8.4 µg/m³, 1.0× usual Kelowna, 15 August: 17.2 µg/m³, 2.0× usual Kelowna, 16 August: 28.5 µg/m³, 3.4× usual Kelowna, 17 August: 18.6 µg/m³, 2.2× usual Kelowna, 18 August: 18.1 µg/m³, 2.2× usual Kelowna, 19 August: 18.0 µg/m³, 2.1× usual Butte Butte, 7 August: 59.8 µg/m³, 7.6× usual Butte, 8 August: 57.6 µg/m³, 7.3× usual Butte, 9 August: 36.1 µg/m³, 4.6× usual Butte, 10 August: 33.3 µg/m³, 4.2× usual Butte, 11 August: 32.3 µg/m³, 4.1× usual Butte, 12 August: 25.5 µg/m³, 3.2× usual Butte, 13 August: 12.1 µg/m³, 1.5× usual Butte, 14 August: 4.8 µg/m³, 0.6× usual Butte, 15 August: 4.3 µg/m³, 0.5× usual Butte, 16 August: 3.6 µg/m³, 0.5× usual Butte, 17 August: 3.5 µg/m³, 0.4× usual Butte, 18 August: 6.2 µg/m³, 0.8× usual Butte, 19 August: 11.6 µg/m³, 1.5× usual Lewiston Lewiston, 7 August: 51.9 µg/m³, 5.1× usual Lewiston, 8 August: 27.0 µg/m³, 2.7× usual Lewiston, 9 August: 22.8 µg/m³, 2.3× usual Lewiston, 10 August: 19.9 µg/m³, 2.0× usual Lewiston, 11 August: 22.2 µg/m³, 2.2× usual Lewiston, 12 August: 16.9 µg/m³, 1.7× usual Lewiston, 13 August: 29.3 µg/m³, 2.9× usual Lewiston, 14 August: 21.4 µg/m³, 2.1× usual Lewiston, 15 August: 21.6 µg/m³, 2.1× usual Lewiston, 16 August: 14.5 µg/m³, 1.4× usual Lewiston, 17 August: 12.4 µg/m³, 1.2× usual Lewiston, 18 August: 13.9 µg/m³, 1.4× usual Lewiston, 19 August: 24.3 µg/m³, 2.4× usual Walla Walla Walla Walla, 7 August: 51.0 µg/m³, 7.1× usual Walla Walla, 8 August: 18.4 µg/m³, 2.6× usual Walla Walla, 9 August: 8.0 µg/m³, 1.1× usual Walla Walla, 10 August: 10.3 µg/m³, 1.4× usual Walla Walla, 11 August: 11.0 µg/m³, 1.5× usual Walla Walla, 12 August: 14.0 µg/m³, 1.9× usual Walla Walla, 13 August: 24.3 µg/m³, 3.4× usual Walla Walla, 14 August: 20.0 µg/m³, 2.8× usual Walla Walla, 15 August: 21.4 µg/m³, 3.0× usual Walla Walla, 16 August: 31.1 µg/m³, 4.3× usual Walla Walla, 17 August: 18.2 µg/m³, 2.5× usual Walla Walla, 18 August: 16.7 µg/m³, 2.3× usual Walla Walla, 19 August: 19.6 µg/m³, 2.7× usual Spokane Spokane, 7 August: 49.3 µg/m³, 5.4× usual Spokane, 8 August: 50.0 µg/m³, 5.4× usual Spokane, 9 August: 75.2 µg/m³, 8.2× usual Spokane, 10 August: 36.5 µg/m³, 4.0× usual Spokane, 11 August: 24.4 µg/m³, 2.7× usual Spokane, 12 August: 28.4 µg/m³, 3.1× usual Spokane, 13 August: 18.5 µg/m³, 2.0× usual Spokane, 14 August: 8.4 µg/m³, 0.9× usual Spokane, 15 August: 11.9 µg/m³, 1.3× usual Spokane, 16 August: 13.0 µg/m³, 1.4× usual Spokane, 17 August: 13.9 µg/m³, 1.5× usual Spokane, 18 August: 17.4 µg/m³, 1.9× usual Spokane, 19 August: 15.3 µg/m³, 1.7× usual Pendleton Pendleton, 7 August: 48.1 µg/m³, 6.2× usual Pendleton, 8 August: 31.4 µg/m³, 4.1× usual Pendleton, 9 August: 14.6 µg/m³, 1.9× usual Pendleton, 10 August: 14.8 µg/m³, 1.9× usual Pendleton, 11 August: 15.8 µg/m³, 2.1× usual Pendleton, 12 August: 12.2 µg/m³, 1.6× usual Pendleton, 13 August: 20.9 µg/m³, 2.7× usual Pendleton, 14 August: 21.4 µg/m³, 2.8× usual Pendleton, 15 August: 29.7 µg/m³, 3.9× usual Pendleton, 16 August: 26.9 µg/m³, 3.5× usual Pendleton, 17 August: 26.2 µg/m³, 3.4× usual Pendleton, 18 August: 15.1 µg/m³, 2.0× usual Pendleton, 19 August: 17.2 µg/m³, 2.2× usual Spokane Valley Spokane Valley, 7 August: 46.5 µg/m³, 5.2× usual Spokane Valley, 8 August: 59.8 µg/m³, 6.6× usual Spokane Valley, 9 August: 82.8 µg/m³, 9.2× usual Spokane Valley, 10 August: 33.8 µg/m³, 3.8× usual Spokane Valley, 11 August: 27.9 µg/m³, 3.1× usual Spokane Valley, 12 August: 29.9 µg/m³, 3.3× usual Spokane Valley, 13 August: 17.8 µg/m³, 2.0× usual Spokane Valley, 14 August: 8.4 µg/m³, 0.9× usual Spokane Valley, 15 August: 12.1 µg/m³, 1.3× usual Spokane Valley, 16 August: 12.6 µg/m³, 1.4× usual Spokane Valley, 17 August: 13.7 µg/m³, 1.5× usual Spokane Valley, 18 August: 17.8 µg/m³, 2.0× usual Spokane Valley, 19 August: 16.5 µg/m³, 1.8× usual Bozeman Bozeman, 7 August: 44.8 µg/m³, 5.6× usual Bozeman, 8 August: 65.0 µg/m³, 8.1× usual Bozeman, 9 August: 45.7 µg/m³, 5.7× usual Bozeman, 10 August: 61.0 µg/m³, 7.6× usual Bozeman, 11 August: 42.8 µg/m³, 5.4× usual Bozeman, 12 August: 26.0 µg/m³, 3.3× usual Bozeman, 13 August: 13.1 µg/m³, 1.6× usual Bozeman, 14 August: 5.3 µg/m³, 0.7× usual Bozeman, 15 August: 5.3 µg/m³, 0.7× usual Bozeman, 16 August: 5.9 µg/m³, 0.7× usual Bozeman, 17 August: 4.8 µg/m³, 0.6× usual Bozeman, 18 August: 5.7 µg/m³, 0.7× usual Bozeman, 19 August: 9.7 µg/m³, 1.2× usual Moses Lake Moses Lake, 7 August: 40.4 µg/m³, 5.4× usual Moses Lake, 8 August: 44.9 µg/m³, 6.0× usual Moses Lake, 9 August: 87.1 µg/m³, 12× usual Moses Lake, 10 August: 36.3 µg/m³, 4.8× usual Moses Lake, 11 August: 42.0 µg/m³, 5.6× usual Moses Lake, 12 August: 36.4 µg/m³, 4.9× usual Moses Lake, 13 August: 16.5 µg/m³, 2.2× usual Moses Lake, 14 August: 10.7 µg/m³, 1.4× usual Moses Lake, 15 August: 18.8 µg/m³, 2.5× usual Moses Lake, 16 August: 21.0 µg/m³, 2.8× usual Moses Lake, 17 August: 21.9 µg/m³, 2.9× usual Moses Lake, 18 August: 17.7 µg/m³, 2.4× usual Moses Lake, 19 August: 15.2 µg/m³, 2.0× usual Missoula Missoula, 7 August: 37.6 µg/m³, 5.2× usual Missoula, 8 August: 26.9 µg/m³, 3.7× usual Missoula, 9 August: 46.7 µg/m³, 6.4× usual Missoula, 10 August: 55.1 µg/m³, 7.5× usual Missoula, 11 August: 47.1 µg/m³, 6.5× usual Missoula, 12 August: 30.5 µg/m³, 4.2× usual Missoula, 13 August: 7.8 µg/m³, 1.1× usual Missoula, 14 August: 8.9 µg/m³, 1.2× usual Missoula, 15 August: 8.8 µg/m³, 1.2× usual Missoula, 16 August: 3.0 µg/m³, 0.4× usual Missoula, 17 August: 3.6 µg/m³, 0.5× usual Missoula, 18 August: 8.8 µg/m³, 1.2× usual Missoula, 19 August: 14.2 µg/m³, 1.9× usual Helena Helena, 7 August: 35.3 µg/m³, 3.8× usual Helena, 8 August: 30.3 µg/m³, 3.2× usual Helena, 9 August: 29.0 µg/m³, 3.1× usual Helena, 10 August: 32.9 µg/m³, 3.5× usual Helena, 11 August: 32.2 µg/m³, 3.4× usual Helena, 12 August: 20.7 µg/m³, 2.2× usual Helena, 13 August: 4.1 µg/m³, 0.4× usual Helena, 14 August: 3.0 µg/m³, 0.3× usual Helena, 15 August: 5.1 µg/m³, 0.5× usual Helena, 16 August: 5.7 µg/m³, 0.6× usual Helena, 17 August: 5.5 µg/m³, 0.6× usual Helena, 18 August: 6.4 µg/m³, 0.7× usual Helena, 19 August: 14.0 µg/m³, 1.5× usual Tri-Cities Tri-Cities, 7 August: 33.0 µg/m³, 5.8× usual Tri-Cities, 8 August: 23.0 µg/m³, 4.0× usual Tri-Cities, 9 August: 13.9 µg/m³, 2.4× usual Tri-Cities, 10 August: 6.7 µg/m³, 1.2× usual Tri-Cities, 11 August: 5.4 µg/m³, 0.9× usual Tri-Cities, 12 August: 18.5 µg/m³, 3.2× usual Tri-Cities, 13 August: 27.8 µg/m³, 4.9× usual Tri-Cities, 14 August: 11.8 µg/m³, 2.1× usual Tri-Cities, 15 August: 17.8 µg/m³, 3.1× usual Tri-Cities, 16 August: 22.1 µg/m³, 3.9× usual Tri-Cities, 17 August: 15.6 µg/m³, 2.7× usual Tri-Cities, 18 August: 13.1 µg/m³, 2.3× usual Tri-Cities, 19 August: 14.7 µg/m³, 2.6× usual Pasco Pasco, 7 August: 32.3 µg/m³, 6.5× usual Pasco, 8 August: 19.0 µg/m³, 3.8× usual Pasco, 9 August: 11.8 µg/m³, 2.4× usual Pasco, 10 August: 6.1 µg/m³, 1.2× usual Pasco, 11 August: 5.7 µg/m³, 1.1× usual Pasco, 12 August: 17.4 µg/m³, 3.5× usual Pasco, 13 August: 26.1 µg/m³, 5.2× usual Pasco, 14 August: 13.2 µg/m³, 2.6× usual Pasco, 15 August: 19.6 µg/m³, 3.9× usual Pasco, 16 August: 27.1 µg/m³, 5.4× usual Pasco, 17 August: 18.1 µg/m³, 3.6× usual Pasco, 18 August: 13.3 µg/m³, 2.7× usual Pasco, 19 August: 15.5 µg/m³, 3.1× usual Sheridan Sheridan, 7 August: 29.1 µg/m³, 4.3× usual Sheridan, 8 August: 36.8 µg/m³, 5.4× usual Sheridan, 9 August: 34.8 µg/m³, 5.1× usual Sheridan, 10 August: 30.1 µg/m³, 4.4× usual Sheridan, 11 August: 22.0 µg/m³, 3.2× usual Sheridan, 12 August: 20.2 µg/m³, 3.0× usual Sheridan, 13 August: 15.0 µg/m³, 2.2× usual Sheridan, 14 August: 9.0 µg/m³, 1.3× usual Sheridan, 15 August: 8.4 µg/m³, 1.2× usual Sheridan, 16 August: 5.9 µg/m³, 0.9× usual Sheridan, 17 August: 4.4 µg/m³, 0.6× usual Sheridan, 18 August: 4.0 µg/m³, 0.6× usual Sheridan, 19 August: 8.6 µg/m³, 1.3× usual Sunnyside Sunnyside, 7 August: 26.8 µg/m³, 3.4× usual Sunnyside, 8 August: 10.8 µg/m³, 1.4× usual Sunnyside, 9 August: 10.6 µg/m³, 1.4× usual Sunnyside, 10 August: 7.6 µg/m³, 1.0× usual Sunnyside, 11 August: 6.9 µg/m³, 0.9× usual Sunnyside, 12 August: 21.2 µg/m³, 2.7× usual Sunnyside, 13 August: 33.9 µg/m³, 4.3× usual Sunnyside, 14 August: 21.8 µg/m³, 2.8× usual Sunnyside, 15 August: 20.8 µg/m³, 2.7× usual Sunnyside, 16 August: 20.0 µg/m³, 2.6× usual Sunnyside, 17 August: 16.3 µg/m³, 2.1× usual Sunnyside, 18 August: 14.7 µg/m³, 1.9× usual Sunnyside, 19 August: 12.8 µg/m³, 1.6× usual Billings Billings, 7 August: 24.8 µg/m³, 3.4× usual Billings, 8 August: 41.4 µg/m³, 5.7× usual Billings, 9 August: 40.6 µg/m³, 5.6× usual Billings, 10 August: 32.3 µg/m³, 4.4× usual Billings, 11 August: 26.1 µg/m³, 3.6× usual Billings, 12 August: 20.6 µg/m³, 2.8× usual Billings, 13 August: 10.1 µg/m³, 1.4× usual Billings, 14 August: 3.6 µg/m³, 0.5× usual Billings, 15 August: 8.1 µg/m³, 1.1× usual Billings, 16 August: 7.5 µg/m³, 1.0× usual Billings, 17 August: 5.7 µg/m³, 0.8× usual Billings, 18 August: 7.0 µg/m³, 1.0× usual Billings, 19 August: 9.1 µg/m³, 1.2× usual Great Falls Great Falls, 7 August: 23.6 µg/m³, 1.8× usual Great Falls, 8 August: 40.5 µg/m³, 3.0× usual Great Falls, 9 August: 37.3 µg/m³, 2.8× usual Great Falls, 10 August: 44.5 µg/m³, 3.3× usual Great Falls, 11 August: 33.4 µg/m³, 2.5× usual Great Falls, 12 August: 20.9 µg/m³, 1.6× usual Great Falls, 13 August: 12.8 µg/m³, 1.0× usual Great Falls, 14 August: 9.5 µg/m³, 0.7× usual Great Falls, 15 August: 8.2 µg/m³, 0.6× usual Great Falls, 16 August: 11.0 µg/m³, 0.8× usual Great Falls, 17 August: 12.9 µg/m³, 1.0× usual Great Falls, 18 August: 15.8 µg/m³, 1.2× usual Great Falls, 19 August: 21.9 µg/m³, 1.6× usual Yakima Yakima, 7 August: 24.6 µg/m³, 4.0× usual Yakima, 8 August: 10.4 µg/m³, 1.7× usual Yakima, 9 August: 36.2 µg/m³, 5.8× usual Yakima, 10 August: 2.8 µg/m³, 0.5× usual Yakima, 11 August: 6.3 µg/m³, 1.0× usual Yakima, 12 August: 25.9 µg/m³, 4.2× usual Yakima, 13 August: 48.5 µg/m³, 7.8× usual Yakima, 14 August: 27.1 µg/m³, 4.4× usual Yakima, 15 August: 28.4 µg/m³, 4.6× usual Yakima, 16 August: 22.0 µg/m³, 3.5× usual Yakima, 17 August: 15.3 µg/m³, 2.5× usual Yakima, 18 August: 18.2 µg/m³, 2.9× usual Yakima, 19 August: 14.2 µg/m³, 2.3× usual Redmond Redmond, 7 August: 21.4 µg/m³, 1.7× usual Redmond, 8 August: 14.2 µg/m³, 1.2× usual Redmond, 9 August: 13.3 µg/m³, 1.1× usual Redmond, 10 August: 34.2 µg/m³, 2.8× usual Redmond, 11 August: 34.7 µg/m³, 2.8× usual Redmond, 12 August: 16.7 µg/m³, 1.4× usual Redmond, 13 August: 25.9 µg/m³, 2.1× usual Redmond, 14 August: 25.0 µg/m³, 2.0× usual Redmond, 15 August: 23.2 µg/m³, 1.9× usual Redmond, 16 August: 20.0 µg/m³, 1.6× usual Redmond, 17 August: 39.2 µg/m³, 3.2× usual Redmond, 18 August: 30.7 µg/m³, 2.5× usual Redmond, 19 August: 29.4 µg/m³, 2.4× usual Red Deer Red Deer, 7 August: 8.9 µg/m³, 0.7× usual Red Deer, 8 August: 15.3 µg/m³, 1.2× usual Red Deer, 9 August: 21.2 µg/m³, 1.7× usual Red Deer, 10 August: 28.7 µg/m³, 2.3× usual Red Deer, 11 August: 15.2 µg/m³, 1.2× usual Red Deer, 12 August: 7.4 µg/m³, 0.6× usual Red Deer, 13 August: 6.5 µg/m³, 0.5× usual Red Deer, 14 August: 5.3 µg/m³, 0.4× usual Red Deer, 15 August: 7.4 µg/m³, 0.6× usual Red Deer, 16 August: 10.2 µg/m³, 0.8× usual Red Deer, 17 August: no reading Red Deer, 18 August: 11.0 µg/m³, 0.9× usual Red Deer, 19 August: 9.0 µg/m³, 0.7× usual Lethbridge Lethbridge, 7 August: 19.2 µg/m³, 2.1× usual Lethbridge, 8 August: 21.3 µg/m³, 2.3× usual Lethbridge, 9 August: 19.6 µg/m³, 2.1× usual Lethbridge, 10 August: 22.1 µg/m³, 2.4× usual Lethbridge, 11 August: 33.4 µg/m³, 3.6× usual Lethbridge, 12 August: 10.6 µg/m³, 1.1× usual Lethbridge, 13 August: 7.7 µg/m³, 0.8× usual Lethbridge, 14 August: 6.8 µg/m³, 0.7× usual Lethbridge, 15 August: 7.0 µg/m³, 0.8× usual Lethbridge, 16 August: 11.9 µg/m³, 1.3× usual Lethbridge, 17 August: 15.4 µg/m³, 1.7× usual Lethbridge, 18 August: 38.7 µg/m³, 4.2× usual Lethbridge, 19 August: 27.5 µg/m³, 3.0× usual Ellensburg Ellensburg, 7 August: 24.7 µg/m³, 4.4× usual Ellensburg, 8 August: 12.4 µg/m³, 2.2× usual Ellensburg, 9 August: 19.5 µg/m³, 3.5× usual Ellensburg, 10 August: 8.5 µg/m³, 1.5× usual Ellensburg, 11 August: 8.5 µg/m³, 1.5× usual Ellensburg, 12 August: 17.9 µg/m³, 3.2× usual Ellensburg, 13 August: 60.6 µg/m³, 11× usual Ellensburg, 14 August: 46.2 µg/m³, 8.3× usual Ellensburg, 15 August: 33.3 µg/m³, 5.9× usual Ellensburg, 16 August: 18.9 µg/m³, 3.4× usual Ellensburg, 17 August: 14.6 µg/m³, 2.6× usual Ellensburg, 18 August: 17.8 µg/m³, 3.2× usual Ellensburg, 19 August: 13.5 µg/m³, 2.4× usual Bend Bend, 7 August: 18.0 µg/m³, 1.8× usual Bend, 8 August: 12.3 µg/m³, 1.2× usual Bend, 9 August: 4.7 µg/m³, 0.5× usual Bend, 10 August: 23.7 µg/m³, 2.4× usual Bend, 11 August: 23.3 µg/m³, 2.4× usual Bend, 12 August: 6.5 µg/m³, 0.7× usual Bend, 13 August: 25.4 µg/m³, 2.6× usual Bend, 14 August: 18.3 µg/m³, 1.8× usual Bend, 15 August: 17.6 µg/m³, 1.8× usual Bend, 16 August: 11.1 µg/m³, 1.1× usual Bend, 17 August: 15.1 µg/m³, 1.5× usual Bend, 18 August: 7.6 µg/m³, 0.8× usual Bend, 19 August: 12.0 µg/m³, 1.2× usual Chilliwack Chilliwack, 7 August: 19.9 µg/m³, 3.5× usual Chilliwack, 8 August: 9.5 µg/m³, 1.7× usual Chilliwack, 9 August: 5.7 µg/m³, 1.0× usual Chilliwack, 10 August: 6.0 µg/m³, 1.1× usual Chilliwack, 11 August: 4.7 µg/m³, 0.8× usual Chilliwack, 12 August: 6.5 µg/m³, 1.1× usual Chilliwack, 13 August: 21.9 µg/m³, 3.8× usual Chilliwack, 14 August: 33.5 µg/m³, 5.9× usual Chilliwack, 15 August: 15.2 µg/m³, 2.7× usual Chilliwack, 16 August: 6.7 µg/m³, 1.2× usual Chilliwack, 17 August: 12.3 µg/m³, 2.2× usual Chilliwack, 18 August: 13.8 µg/m³, 2.4× usual Chilliwack, 19 August: 9.8 µg/m³, 1.7× usual The Dalles The Dalles, 7 August: 19.3 µg/m³, 3.6× usual The Dalles, 8 August: 11.2 µg/m³, 2.1× usual The Dalles, 9 August: 5.0 µg/m³, 0.9× usual The Dalles, 10 August: 5.3 µg/m³, 1.0× usual The Dalles, 11 August: 5.8 µg/m³, 1.1× usual The Dalles, 12 August: 5.1 µg/m³, 1.0× usual The Dalles, 13 August: 22.8 µg/m³, 4.3× usual The Dalles, 14 August: 28.6 µg/m³, 5.4× usual The Dalles, 15 August: 18.7 µg/m³, 3.5× usual The Dalles, 16 August: 10.8 µg/m³, 2.0× usual The Dalles, 17 August: 12.2 µg/m³, 2.3× usual The Dalles, 18 August: 14.7 µg/m³, 2.8× usual The Dalles, 19 August: 23.6 µg/m³, 4.5× usual Kennewick Kennewick, 7 August: 32.0 µg/m³, 4.8× usual Kennewick, 8 August: 20.0 µg/m³, 3.0× usual Kennewick, 9 August: 14.0 µg/m³, 2.1× usual Kennewick, 10 August: 6.5 µg/m³, 1.0× usual Kennewick, 11 August: 6.1 µg/m³, 0.9× usual Kennewick, 12 August: 14.6 µg/m³, 2.2× usual Kennewick, 13 August: 26.4 µg/m³, 3.9× usual Kennewick, 14 August: 12.9 µg/m³, 1.9× usual Kennewick, 15 August: 17.5 µg/m³, 2.6× usual Kennewick, 16 August: 25.2 µg/m³, 3.8× usual Kennewick, 17 August: 20.1 µg/m³, 3.0× usual Kennewick, 18 August: 13.7 µg/m³, 2.0× usual Kennewick, 19 August: 15.2 µg/m³, 2.3× usual 7 Aug 9 11 13 15 17 19 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. Good 0–50
Moderate 51–100
Sensitive groups 101–150
Unhealthy 151–200
Very unhealthy 201–300
Hazardous 301+
Every city it reached
City Days Highest Usual Above usual
Wenatchee Washington, United States 5 7 August 5.0 20× Kamloops British Columbia, Canada 1 7 August 11.2 17× Vernon British Columbia, Canada 3 10 August 9.1 16× Moses Lake Washington, United States 3 9 August 7.5 12× Kelowna British Columbia, Canada 2 11 August 8.4 11× Ellensburg Washington, United States 3 13 August 5.6 11× Cranbrook British Columbia, Canada 3 9 August 8.9 10× Spokane Valley Washington, United States 3 9 August 9.0 9.2× Spokane Washington, United States 2 9 August 9.2 8.2× Bozeman Montana, United States 3 8 August 8.0 8.1× Yakima Washington, United States 4 13 August 6.2 7.8× Nampa Idaho, United States 1 7 August 10.0 7.8× Butte Montana, United States 3 7 August 7.9 7.6× Missoula Montana, United States 3 10 August 7.3 7.5× Walla Walla Washington, United States 1 7 August 7.2 7.1× Pasco Washington, United States 2 7 August 4.0 6.5× Pendleton Oregon, United States 2 7 August 7.7 6.2× Chilliwack British Columbia, Canada 1 14 August 5.7 5.9× Tri-Cities Washington, United States 1 7 August 5.7 5.8× Billings Montana, United States 2 8 August 7.3 5.7× Sheridan Wyoming, United States 1 8 August 6.8 5.4× The Dalles Oregon, United States 1 14 August 5.3 5.4× Lewiston Idaho, United States 1 7 August 10.1 5.1× Kennewick Washington, United States 1 7 August 6.7 4.8× Sunnyside Washington, United States 1 13 August 7.8 4.3× Lethbridge Alberta, Canada 1 18 August 9.3 4.2× Helena Montana, United States 2 7 August 9.4 3.8× Great Falls Montana, United States 2 10 August 13.3 3.3× Redmond Oregon, United States 2 17 August 12.3 3.2× Bend Oregon, United States 1 13 August 9.9 2.6× Red Deer Alberta, Canada 1 10 August 12.3 2.3×
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 28 of 106 episodes in the United States and Canada since our records began, by cities reached.
North-eastern United States and Canada, June and July 2023 279 North-eastern United States and Canada, July 2026 264 North-eastern United States and Canada, May and June 2023 260 North-eastern United States and Canada, July and August 2025 241 North-eastern United States and Canada, July 2023 241 North-eastern United States and Canada, June 2025 196 North-eastern United States and Canada, June 2023 161 North-eastern United States and Canada, July 2025 119 North-western United States and Canada, August 2023 110 North-eastern United States, June 2025 104 North-western United States and Canada, August 2026 99 North-eastern United States and Canada, February 2026 96 North-western United States and Canada, August 2026 31 Bars: cities reached; colour: the level of the episode's highest daily reading. All 106 .
Use this page SmogRank, North-western United States and Canada, August 2026: 31 cities with PM2.5 at twice their usual or more, 10 to 16 August 2026, smogrank.com/episodes/2026-08-north-western-united-states-and-canada-2 (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.
