SmogRank / Episodes / Canada
North-western Canada and United States, June 2025
For 6 days, from 7 to 12 June 2025, 14 cities in Canada and the United States had PM2.5 at least twice their usual for the time of year. The worst reading was Saskatoon, Saskatchewan, Canada: 125.0 µg/m³ on 10 June, about 20× its usual 6.3.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 14 in 2 countries
Days 6 7 to 12 June 2025
Worst day 10 June 12 cities counted
Furthest above usual 24× Prince Albert
Day by day
Play 10 June 12 cities at twice their usual or more
Helena Bozeman Butte Missoula Great Falls Billings St. Albert Edmonton Prince Albert Sherwood Park Red Deer Medicine Hat Airdrie Calgary Regina Saskatoon Swift Current Lethbridge 4 Jun 5 6 7 8 9 10 11 12 13 14 15 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
Prince Albert Prince Albert, 4 June: 52.5 µg/m³, 7.2× usual Prince Albert, 5 June: 249.0 µg/m³, 34× usual Prince Albert, 6 June: 11.3 µg/m³, 1.5× usual Prince Albert, 7 June: 19.2 µg/m³, 2.6× usual Prince Albert, 8 June: 13.6 µg/m³, 1.9× usual Prince Albert, 9 June: 37.4 µg/m³, 5.1× usual Prince Albert, 10 June: 105.0 µg/m³, 14× usual Prince Albert, 11 June: 52.1 µg/m³, 7.1× usual Prince Albert, 12 June: 12.6 µg/m³, 1.7× usual Prince Albert, 13 June: 20.9 µg/m³, 2.9× usual Prince Albert, 14 June: 18.4 µg/m³, 2.5× usual Prince Albert, 15 June: 6.0 µg/m³, 0.8× usual Medicine Hat Medicine Hat, 4 June: 25.5 µg/m³, 5.1× usual Medicine Hat, 5 June: 7.5 µg/m³, 1.5× usual Medicine Hat, 6 June: 6.4 µg/m³, 1.3× usual Medicine Hat, 7 June: 20.3 µg/m³, 4.1× usual Medicine Hat, 8 June: 28.4 µg/m³, 5.7× usual Medicine Hat, 9 June: 25.9 µg/m³, 5.2× usual Medicine Hat, 10 June: 69.0 µg/m³, 14× usual Medicine Hat, 11 June: 85.1 µg/m³, 17× usual Medicine Hat, 12 June: 51.2 µg/m³, 10× usual Medicine Hat, 13 June: 11.1 µg/m³, 2.2× usual Medicine Hat, 14 June: 5.3 µg/m³, 1.1× usual Medicine Hat, 15 June: 5.3 µg/m³, 1.1× usual Saskatoon Saskatoon, 4 June: 14.9 µg/m³, 2.4× usual Saskatoon, 5 June: 30.3 µg/m³, 4.8× usual Saskatoon, 6 June: 10.8 µg/m³, 1.7× usual Saskatoon, 7 June: 25.3 µg/m³, 4.0× usual Saskatoon, 8 June: 12.1 µg/m³, 1.9× usual Saskatoon, 9 June: 37.9 µg/m³, 6.0× usual Saskatoon, 10 June: 125.0 µg/m³, 20× usual Saskatoon, 11 June: 96.5 µg/m³, 15× usual Saskatoon, 12 June: 45.5 µg/m³, 7.2× usual Saskatoon, 13 June: 38.9 µg/m³, 6.2× usual Saskatoon, 14 June: 16.0 µg/m³, 2.5× usual Saskatoon, 15 June: 6.7 µg/m³, 1.1× usual Calgary Calgary, 4 June: 10.6 µg/m³, 1.8× usual Calgary, 5 June: 8.2 µg/m³, 1.4× usual Calgary, 6 June: 6.7 µg/m³, 1.1× usual Calgary, 7 June: 33.5 µg/m³, 5.6× usual Calgary, 8 June: 43.7 µg/m³, 7.3× usual Calgary, 9 June: 32.0 µg/m³, 5.3× usual Calgary, 10 June: 41.6 µg/m³, 6.9× usual Calgary, 11 June: 110.5 µg/m³, 18× usual Calgary, 12 June: 45.8 µg/m³, 7.6× usual Calgary, 13 June: 17.7 µg/m³, 2.9× usual Calgary, 14 June: 5.6 µg/m³, 0.9× usual Calgary, 15 June: 5.5 µg/m³, 0.9× usual Regina Regina, 4 June: 19.9 µg/m³, 4.0× usual Regina, 5 June: 23.0 µg/m³, 4.6× usual Regina, 6 June: 12.0 µg/m³, 2.4× usual Regina, 7 June: 31.1 µg/m³, 6.2× usual Regina, 8 June: 15.9 µg/m³, 3.2× usual Regina, 9 June: 21.9 µg/m³, 4.4× usual Regina, 10 June: 94.9 µg/m³, 19× usual Regina, 11 June: 73.3 µg/m³, 15× usual Regina, 12 June: 60.2 µg/m³, 12× usual Regina, 13 June: 29.1 µg/m³, 5.8× usual Regina, 14 June: 8.4 µg/m³, 1.7× usual Regina, 15 June: 6.8 µg/m³, 1.4× usual Airdrie Airdrie, 4 June: 7.2 µg/m³, 1.4× usual Airdrie, 5 June: 5.8 µg/m³, 1.2× usual Airdrie, 6 June: 5.0 µg/m³, 1.0× usual Airdrie, 7 June: 30.9 µg/m³, 6.2× usual Airdrie, 8 June: 36.8 µg/m³, 7.4× usual Airdrie, 9 June: 24.2 µg/m³, 4.8× usual Airdrie, 10 June: 38.8 µg/m³, 7.8× usual Airdrie, 11 June: 86.9 µg/m³, 17× usual Airdrie, 12 June: 41.4 µg/m³, 8.3× usual Airdrie, 13 June: 15.1 µg/m³, 3.0× usual Airdrie, 14 June: 3.3 µg/m³, 0.7× usual Airdrie, 15 June: 3.4 µg/m³, 0.7× usual Lethbridge Lethbridge, 4 June: 12.0 µg/m³, 2.4× usual Lethbridge, 5 June: 5.7 µg/m³, 1.1× usual Lethbridge, 6 June: 5.0 µg/m³, 1.0× usual Lethbridge, 7 June: 27.2 µg/m³, 5.4× usual Lethbridge, 8 June: 49.7 µg/m³, 9.9× usual Lethbridge, 9 June: 14.8 µg/m³, 3.0× usual Lethbridge, 10 June: 33.9 µg/m³, 6.8× usual Lethbridge, 11 June: 121.0 µg/m³, 24× usual Lethbridge, 12 June: 48.1 µg/m³, 9.6× usual Lethbridge, 13 June: 5.3 µg/m³, 1.1× usual Lethbridge, 14 June: 5.3 µg/m³, 1.1× usual Lethbridge, 15 June: 4.6 µg/m³, 0.9× usual Red Deer Red Deer, 4 June: 17.6 µg/m³, 3.1× usual Red Deer, 5 June: 11.2 µg/m³, 2.0× usual Red Deer, 6 June: 7.4 µg/m³, 1.3× usual Red Deer, 7 June: 26.3 µg/m³, 4.6× usual Red Deer, 8 June: 41.1 µg/m³, 7.2× usual Red Deer, 9 June: 27.9 µg/m³, 4.9× usual Red Deer, 10 June: 39.5 µg/m³, 6.9× usual Red Deer, 11 June: 82.2 µg/m³, 14× usual Red Deer, 12 June: 69.8 µg/m³, 12× usual Red Deer, 13 June: 23.5 µg/m³, 4.1× usual Red Deer, 14 June: 4.0 µg/m³, 0.7× usual Red Deer, 15 June: 5.5 µg/m³, 1.0× usual Edmonton Edmonton, 4 June: 22.0 µg/m³, 3.1× usual Edmonton, 5 June: 13.8 µg/m³, 2.0× usual Edmonton, 6 June: 6.2 µg/m³, 0.9× usual Edmonton, 7 June: 16.9 µg/m³, 2.4× usual Edmonton, 8 June: 36.8 µg/m³, 5.3× usual Edmonton, 9 June: 24.0 µg/m³, 3.4× usual Edmonton, 10 June: 85.2 µg/m³, 12× usual Edmonton, 11 June: 89.2 µg/m³, 13× usual Edmonton, 12 June: 24.2 µg/m³, 3.5× usual Edmonton, 13 June: 29.3 µg/m³, 4.2× usual Edmonton, 14 June: 8.9 µg/m³, 1.3× usual Edmonton, 15 June: 9.1 µg/m³, 1.3× usual Sherwood Park Sherwood Park, 4 June: 22.1 µg/m³, 4.2× usual Sherwood Park, 5 June: 10.8 µg/m³, 2.0× usual Sherwood Park, 6 June: 4.1 µg/m³, 0.8× usual Sherwood Park, 7 June: 14.6 µg/m³, 2.8× usual Sherwood Park, 8 June: 34.1 µg/m³, 6.4× usual Sherwood Park, 9 June: 25.0 µg/m³, 4.7× usual Sherwood Park, 10 June: 76.1 µg/m³, 14× usual Sherwood Park, 11 June: no reading Sherwood Park, 12 June: no reading Sherwood Park, 13 June: no reading Sherwood Park, 14 June: 4.9 µg/m³, 0.9× usual Sherwood Park, 15 June: 5.6 µg/m³, 1.1× usual St. Albert St. Albert, 4 June: 15.9 µg/m³, 2.6× usual St. Albert, 5 June: 12.1 µg/m³, 2.0× usual St. Albert, 6 June: 4.4 µg/m³, 0.7× usual St. Albert, 7 June: 19.2 µg/m³, 3.1× usual St. Albert, 8 June: 31.0 µg/m³, 5.0× usual St. Albert, 9 June: 29.4 µg/m³, 4.7× usual St. Albert, 10 June: 68.7 µg/m³, 11× usual St. Albert, 11 June: 58.5 µg/m³, 9.4× usual St. Albert, 12 June: 21.7 µg/m³, 3.5× usual St. Albert, 13 June: 19.2 µg/m³, 3.1× usual St. Albert, 14 June: 4.7 µg/m³, 0.8× usual St. Albert, 15 June: 4.3 µg/m³, 0.7× usual Billings Billings, 4 June: 3.6 µg/m³, 0.7× usual Billings, 5 June: 4.1 µg/m³, 0.8× usual Billings, 6 June: 3.4 µg/m³, 0.7× usual Billings, 7 June: 11.9 µg/m³, 2.4× usual Billings, 8 June: 28.4 µg/m³, 5.7× usual Billings, 9 June: 14.8 µg/m³, 3.0× usual Billings, 10 June: 12.8 µg/m³, 2.6× usual Billings, 11 June: 13.1 µg/m³, 2.6× usual Billings, 12 June: 6.7 µg/m³, 1.3× usual Billings, 13 June: 4.2 µg/m³, 0.8× usual Billings, 14 June: 4.2 µg/m³, 0.8× usual Billings, 15 June: 4.6 µg/m³, 0.9× usual Great Falls Great Falls, 4 June: 9.2 µg/m³, 1.2× usual Great Falls, 5 June: 8.1 µg/m³, 1.1× usual Great Falls, 6 June: 9.7 µg/m³, 1.3× usual Great Falls, 7 June: 10.1 µg/m³, 1.3× usual Great Falls, 8 June: 27.1 µg/m³, 3.6× usual Great Falls, 9 June: 15.5 µg/m³, 2.0× usual Great Falls, 10 June: 11.8 µg/m³, 1.6× usual Great Falls, 11 June: 11.9 µg/m³, 1.6× usual Great Falls, 12 June: 16.0 µg/m³, 2.1× usual Great Falls, 13 June: 9.3 µg/m³, 1.2× usual Great Falls, 14 June: 8.5 µg/m³, 1.1× usual Great Falls, 15 June: 7.3 µg/m³, 1.0× usual Swift Current Swift Current, 4 June: 16.0 µg/m³, 3.2× usual Swift Current, 5 June: 16.2 µg/m³, 3.2× usual Swift Current, 6 June: 8.5 µg/m³, 1.7× usual Swift Current, 7 June: 21.2 µg/m³, 4.2× usual Swift Current, 8 June: 13.3 µg/m³, 2.7× usual Swift Current, 9 June: 16.8 µg/m³, 3.4× usual Swift Current, 10 June: 117.0 µg/m³, 23× usual Swift Current, 11 June: 84.1 µg/m³, 17× usual Swift Current, 12 June: 49.2 µg/m³, 9.8× usual Swift Current, 13 June: 20.1 µg/m³, 4.0× usual Swift Current, 14 June: 7.5 µg/m³, 1.5× usual Swift Current, 15 June: 4.7 µg/m³, 0.9× usual 4 Jun 6 8 10 12 14 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
Prince Albert Saskatchewan, Canada 2 5 June 7.3 34× Lethbridge Alberta, Canada 5 11 June 4.4 24× Swift Current Saskatchewan, Canada 3 10 June 4.4 23× Saskatoon Saskatchewan, Canada 3 10 June 6.3 20× Regina Saskatchewan, Canada 3 10 June 5.0 19× Calgary Alberta, Canada 6 11 June 6.0 18× Airdrie Alberta, Canada 5 11 June 5.0 17× Medicine Hat Alberta, Canada 5 11 June 3.9 17× Red Deer Alberta, Canada 6 11 June 5.7 14× Sherwood Park Alberta, Canada 3 10 June 5.3 14× Edmonton Alberta, Canada 3 11 June 7.0 13× St. Albert Alberta, Canada 4 10 June 6.2 11× Billings Montana, United States 1 8 June 4.5 5.7× Great Falls Montana, United States 1 8 June 7.6 3.6×
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 Canada and the United States
Number 58 of 106 episodes in Canada and the United States 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 Canada and United States, June 2025 14 Bars: cities reached; colour: the level of the episode's highest daily reading. All 106 .
Use this page SmogRank, North-western Canada and United States, June 2025: 14 cities with PM2.5 at twice their usual or more, 7 to 12 June 2025, smogrank.com/episodes/2025-06-north-western-canada-and-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.
