SmogRank / Episodes / Canada

North-western Canada and United States, 14 to 17 July 2025

For 4 days, from 14 to 17 July 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: 116.0 µg/m³ on 14 July, about 9.5× its usual 12.2. Ended 17 July.

Few fires were detected near these cities on those days. Spreads like this usually come from still weather trapping smoke from heating, traffic and industry, or from dust.
Cities reached14in 2 countries
Days414 to 17 July 2025
Worst day15 July8 cities counted
Furthest above usual9.8×Swift Current

Day by day

15 July 8 cities at twice their usual or more
ReginaLewistownGlendiveEstevanAirdrieCalgaryColumbia FallsRed DeerGreat FallsFort SaskatchewanSt. AlbertGrand CentreEdmontonSherwood ParkLethbridgeHavreFlin FlonPrince AlbertMedicine HatSaskatoonSwift Current
11 Jul121314151617181920
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

SaskatoonSaskatoon, 11 July: 40.9 µg/m³Saskatoon, 12 July: 12.4 µg/m³Saskatoon, 13 July: 4.1 µg/m³Saskatoon, 14 July: 116.0 µg/m³, 9.5× its usual 12.2Saskatoon, 15 July: 99.2 µg/m³, 7.9× its usual 12.5Saskatoon, 16 July: 59.9 µg/m³, 4.6× its usual 12.9Saskatoon, 17 July: 21.6 µg/m³Saskatoon, 18 July: 18.6 µg/m³Saskatoon, 19 July: 21.8 µg/m³Saskatoon, 20 July: 26.6 µg/m³Prince AlbertPrince Albert, 11 July: 185.0 µg/m³Prince Albert, 12 July: 14.5 µg/m³Prince Albert, 13 July: 39.7 µg/m³Prince Albert, 14 July: 106.0 µg/m³, 8.2× its usual 13.0Prince Albert, 15 July: 49.8 µg/m³, 3.8× its usual 13.0Prince Albert, 16 July: 64.0 µg/m³, 4.8× its usual 13.4Prince Albert, 17 July: 32.4 µg/m³, 2.3× its usual 13.8Prince Albert, 18 July: 28.0 µg/m³Prince Albert, 19 July: 60.6 µg/m³Prince Albert, 20 July: 47.2 µg/m³Medicine HatMedicine Hat, 11 July: 8.5 µg/m³Medicine Hat, 12 July: 6.0 µg/m³Medicine Hat, 13 July: 4.1 µg/m³Medicine Hat, 14 July: 41.5 µg/m³, 5.3× its usual 7.9Medicine Hat, 15 July: 67.6 µg/m³, 8.6× its usual 7.9Medicine Hat, 16 July: 40.5 µg/m³, 5.1× its usual 7.9Medicine Hat, 17 July: 6.6 µg/m³Medicine Hat, 18 July: 6.4 µg/m³Medicine Hat, 19 July: 5.7 µg/m³Medicine Hat, 20 July: 4.3 µg/m³Swift CurrentSwift Current, 11 July: 11.7 µg/m³Swift Current, 12 July: 6.1 µg/m³Swift Current, 13 July: 3.6 µg/m³Swift Current, 14 July: 40.9 µg/m³, 4.8× its usual 8.6Swift Current, 15 July: 85.4 µg/m³, 9.8× its usual 8.7Swift Current, 16 July: 57.3 µg/m³, 6.6× its usual 8.7Swift Current, 17 July: 9.4 µg/m³Swift Current, 18 July: 14.4 µg/m³Swift Current, 19 July: 6.3 µg/m³Swift Current, 20 July: 4.0 µg/m³LethbridgeLethbridge, 11 July: 3.6 µg/m³Lethbridge, 12 July: 4.8 µg/m³Lethbridge, 13 July: 4.0 µg/m³Lethbridge, 14 July: 34.0 µg/m³, 4.3× its usual 8.0Lethbridge, 15 July: 26.3 µg/m³, 3.3× its usual 8.0Lethbridge, 16 July: 19.0 µg/m³Lethbridge, 17 July: 6.6 µg/m³Lethbridge, 18 July: 8.2 µg/m³Lethbridge, 19 July: 4.5 µg/m³Lethbridge, 20 July: 3.9 µg/m³Grand CentreGrand Centre, 11 July: 20.8 µg/m³Grand Centre, 12 July: 5.0 µg/m³Grand Centre, 13 July: 9.6 µg/m³Grand Centre, 14 July: 25.4 µg/m³, 2.4× its usual 10.7Grand Centre, 15 July: 36.3 µg/m³, 3.4× its usual 10.7Grand Centre, 16 July: 24.9 µg/m³Grand Centre, 17 July: 36.5 µg/m³, 3.3× its usual 11.0Grand Centre, 18 July: 57.3 µg/m³Grand Centre, 19 July: 54.1 µg/m³Grand Centre, 20 July: 40.1 µg/m³HavreHavre, 11 July: 4.7 µg/m³Havre, 12 July: 3.6 µg/m³Havre, 13 July: 3.2 µg/m³Havre, 14 July: 6.2 µg/m³Havre, 15 July: 34.8 µg/m³, 5.4× its usual 6.5Havre, 16 July: 12.4 µg/m³Havre, 17 July: 4.1 µg/m³Havre, 18 July: 3.0 µg/m³Havre, 19 July: 3.5 µg/m³Havre, 20 July: 3.3 µg/m³Great FallsGreat Falls, 11 July: 10.8 µg/m³Great Falls, 12 July: 10.0 µg/m³Great Falls, 13 July: 10.5 µg/m³Great Falls, 14 July: 8.5 µg/m³Great Falls, 15 July: 34.4 µg/m³, 2.7× its usual 12.6Great Falls, 16 July: 17.7 µg/m³Great Falls, 17 July: 9.1 µg/m³Great Falls, 18 July: 12.2 µg/m³Great Falls, 19 July: 11.3 µg/m³Great Falls, 20 July: 8.6 µg/m³EdmontonEdmonton, 11 July: 15.6 µg/m³Edmonton, 12 July: 4.1 µg/m³Edmonton, 13 July: 4.1 µg/m³Edmonton, 14 July: 13.7 µg/m³Edmonton, 15 July: 10.9 µg/m³Edmonton, 16 July: 29.1 µg/m³, 2.3× its usual 12.6Edmonton, 17 July: 42.5 µg/m³, 3.4× its usual 12.6Edmonton, 18 July: 16.0 µg/m³Edmonton, 19 July: 20.0 µg/m³Edmonton, 20 July: 30.3 µg/m³Red DeerRed Deer, 11 July: 9.5 µg/m³Red Deer, 12 July: 7.6 µg/m³Red Deer, 13 July: 2.8 µg/m³Red Deer, 14 July: 8.6 µg/m³Red Deer, 15 July: 7.4 µg/m³Red Deer, 16 July: 26.4 µg/m³, 2.6× its usual 10.3Red Deer, 17 July: 27.7 µg/m³, 2.6× its usual 10.6Red Deer, 18 July: 6.8 µg/m³Red Deer, 19 July: 7.3 µg/m³Red Deer, 20 July: 9.4 µg/m³Flin FlonFlin Flon, 11 July: 38.7 µg/m³Flin Flon, 12 July: 42.7 µg/m³Flin Flon, 13 July: 8.8 µg/m³Flin Flon, 14 July: no readingFlin Flon, 15 July: no readingFlin Flon, 16 July: no readingFlin Flon, 17 July: 103.0 µg/m³, 6.9× its usual 15.0Flin Flon, 18 July: 61.3 µg/m³Flin Flon, 19 July: 104.0 µg/m³Flin Flon, 20 July: 78.0 µg/m³Fort SaskatchewanFort Saskatchewan, 11 July: 14.9 µg/m³Fort Saskatchewan, 12 July: 3.8 µg/m³Fort Saskatchewan, 13 July: 3.0 µg/m³Fort Saskatchewan, 14 July: 11.0 µg/m³Fort Saskatchewan, 15 July: 8.2 µg/m³Fort Saskatchewan, 16 July: no readingFort Saskatchewan, 17 July: 34.0 µg/m³, 3.1× its usual 10.8Fort Saskatchewan, 18 July: 13.8 µg/m³Fort Saskatchewan, 19 July: 17.3 µg/m³Fort Saskatchewan, 20 July: 25.7 µg/m³Sherwood ParkSherwood Park, 11 July: no readingSherwood Park, 12 July: no readingSherwood Park, 13 July: no readingSherwood Park, 14 July: no readingSherwood Park, 15 July: no readingSherwood Park, 16 July: no readingSherwood Park, 17 July: 32.2 µg/m³, 3.7× its usual 8.6Sherwood Park, 18 July: 11.3 µg/m³Sherwood Park, 19 July: 14.1 µg/m³Sherwood Park, 20 July: 22.8 µg/m³St. AlbertSt. Albert, 11 July: 8.9 µg/m³St. Albert, 12 July: 2.7 µg/m³St. Albert, 13 July: 2.5 µg/m³St. Albert, 14 July: 8.5 µg/m³St. Albert, 15 July: 6.6 µg/m³St. Albert, 16 July: 21.3 µg/m³St. Albert, 17 July: 28.6 µg/m³, 3.2× its usual 9.0St. Albert, 18 July: 12.1 µg/m³St. Albert, 19 July: 13.7 µg/m³St. Albert, 20 July: 19.6 µg/m³11 Jul121314151617181920
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
Swift CurrentSaskatchewan, Canada3 85.415 July8.79.8×
SaskatoonSaskatchewan, Canada3 116.014 July12.29.5×
Medicine HatAlberta, Canada3 67.615 July7.98.6×
Prince AlbertSaskatchewan, Canada4 106.014 July13.08.2×
Flin FlonManitoba, Canada1 103.017 July15.06.9×
HavreMontana, United States1 34.815 July6.55.4×
LethbridgeAlberta, Canada2 34.014 July8.04.3×
Sherwood ParkAlberta, Canada1 32.217 July8.63.7×
EdmontonAlberta, Canada2 42.517 July12.63.4×
Grand CentreAlberta, Canada3 36.517 July11.03.3×
St. AlbertAlberta, Canada1 28.617 July9.03.2×
Fort SaskatchewanAlberta, Canada1 34.017 July10.83.1×
Great FallsMontana, United States1 34.415 July12.62.7×
Red DeerAlberta, Canada2 27.717 July10.62.6×

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 Canada and the United States

Number 94 of 173 episodes in Canada and the United States 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 Canada and United States, 14 to 17 July 2025: 14 cities with PM2.5 at twice their usual or more, 14 to 17 July 2025, smogrank.com/episodes/2025-07-14-north-western-canada-and-united-states (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.