SmogRank / Episodes / United States
Western United States, January and February 2025
For 5 days, from 29 January to 2 February 2025, 26 cities in the United States and Mexico had PM2.5 at least twice their usual for the time of year. The worst reading was Woodburn, Oregon, United States: 37.8 µg/m³ on 29 January, about 7.6× its usual 5.0.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 26 in 2 countries
Days 5 29 January to 2 February 2025
Worst day 1 February 9 cities counted
Furthest above usual 7.6× Woodburn
Day by day
Play 1 February 9 cities at twice their usual or more
Spanish Springs Carson City Reno South Lake Tahoe Truckee Clovis Summerlin South Ridgecrest Spring Valley Las Vegas Enterprise Henderson Merced Mesquite Boulder City Folsom Turlock Lincoln Modesto Roseville Twin Falls Galt Arden-Arcade Bakersfield Manteca Florin Nampa Stockton Cedar City Hurricane Sacramento Meridian Boise Yuba City Paradise Tracy Lancaster Davis Woodland Victorville Hollister Livermore Vacaville Gilroy Pleasanton Tooele Santa Clarita Concord La Crescenta-Montrose San Jose Martinez Glendora Atascadero Fillmore Prunedale Watsonville Salinas Simi Valley Magna San Leandro Sunnyvale Vallejo Herriman San Luis Obispo Banning Berkeley Oakland West Valley City Agoura Thousand Oaks Live Oak Nipomo West Jordan Arroyo Grande Santa Monica Santa Cruz Redwood City Seaside Inglewood Redding Oxnard Compton Santa Barbara Hawthorne Millcreek Salt Lake City Highland Orcutt Altamont San Francisco Goleta South San Francisco Bountiful Carson Torrance Orem San Rafael Spanish Fork Long Beach Lomita Lake Elsinore North Ogden Indio Brigham City Santa Rosa Lompoc Windsor Temecula Pocatello Oceanside Ukiah Poway Ashland Bend El Cajon Brawley Redmond San Diego Medford Chula Vista Idaho Falls El Centro Pendleton Tijuana Calexico Mexicali Walla Walla Hermiston Tri-Cities Roseburg Pullman Moscow The Dalles Glendale Eugene Tempe Mesa Albany Apache Junction Corvallis Moses Lake Butte Canby Coos Bay Gresham Missoula Casa Grande Tigard Portland Dallas Spokane Spokane Valley Beaverton Coeur d'Alene Vancouver Ellensburg Salmon Creek McMinnville Forest Grove Wenatchee Bozeman Helena Marana Longview Casas Adobes Tucson Centralia Auburn Green Valley Tacoma Lacey Renton Columbia City Bellevue Seattle Bremerton Shoreline Picnic Point-North Lynnwood Great Falls Aberdeen Mount Vernon Oak Harbor Port Angeles Victoria Fresno Visalia Corcoran Phoenix Hanford Porterville Nogales Yakima Anaheim Nogales Madera Los Angeles Sunnyside Lewiston Jurupa Valley Grants Pass Riverside Parkland Fontana Burbank Hillsboro Chico Milwaukie Salem Yuma Woodburn 26 Jan 27 28 29 30 31 1 Feb 2 3 4 5 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
Parkland Parkland, 26 January: 27.3 µg/m³, 4.0× usual Parkland, 27 January: 28.1 µg/m³, 4.1× usual Parkland, 28 January: 29.3 µg/m³, 4.3× usual Parkland, 29 January: 25.0 µg/m³, 3.7× usual Parkland, 30 January: 18.4 µg/m³, 2.7× usual Parkland, 31 January: 3.6 µg/m³, 0.5× usual Parkland, 1 February: 3.3 µg/m³, 0.5× usual Parkland, 2 February: 5.7 µg/m³, 0.8× usual Parkland, 3 February: 4.5 µg/m³, 0.7× usual Parkland, 4 February: 5.8 µg/m³, 0.9× usual Parkland, 5 February: 4.5 µg/m³, 0.7× usual Grants Pass Grants Pass, 26 January: 17.6 µg/m³, 2.0× usual Grants Pass, 27 January: 29.8 µg/m³, 3.5× usual Grants Pass, 28 January: 27.2 µg/m³, 3.2× usual Grants Pass, 29 January: 31.1 µg/m³, 3.6× usual Grants Pass, 30 January: 28.0 µg/m³, 3.3× usual Grants Pass, 31 January: 11.6 µg/m³, 1.3× usual Grants Pass, 1 February: 7.2 µg/m³, 0.8× usual Grants Pass, 2 February: 3.8 µg/m³, 0.4× usual Grants Pass, 3 February: 9.4 µg/m³, 1.1× usual Grants Pass, 4 February: 14.6 µg/m³, 1.7× usual Grants Pass, 5 February: 5.1 µg/m³, 0.6× usual Woodburn Woodburn, 26 January: 3.9 µg/m³, 0.8× usual Woodburn, 27 January: 11.3 µg/m³, 2.3× usual Woodburn, 28 January: 25.2 µg/m³, 5.0× usual Woodburn, 29 January: 37.8 µg/m³, 7.6× usual Woodburn, 30 January: 24.1 µg/m³, 4.8× usual Woodburn, 31 January: 5.5 µg/m³, 1.1× usual Woodburn, 1 February: 2.7 µg/m³, 0.5× usual Woodburn, 2 February: 2.7 µg/m³, 0.5× usual Woodburn, 3 February: 2.9 µg/m³, 0.6× usual Woodburn, 4 February: 11.0 µg/m³, 2.2× usual Woodburn, 5 February: 2.7 µg/m³, 0.5× usual Chico Chico, 26 January: 16.2 µg/m³, 2.0× usual Chico, 27 January: 15.3 µg/m³, 1.9× usual Chico, 28 January: 23.1 µg/m³, 2.9× usual Chico, 29 January: 28.5 µg/m³, 3.5× usual Chico, 30 January: 33.3 µg/m³, 4.1× usual Chico, 31 January: 15.5 µg/m³, 1.9× usual Chico, 1 February: 9.9 µg/m³, 1.2× usual Chico, 2 February: 6.2 µg/m³, 0.8× usual Chico, 3 February: 6.3 µg/m³, 0.8× usual Chico, 4 February: 7.7 µg/m³, 1.0× usual Chico, 5 February: 12.7 µg/m³, 1.6× usual Salem Salem, 26 January: 5.0 µg/m³, 0.8× usual Salem, 27 January: 17.4 µg/m³, 2.9× usual Salem, 28 January: 17.3 µg/m³, 2.9× usual Salem, 29 January: 27.6 µg/m³, 4.6× usual Salem, 30 January: 15.0 µg/m³, 2.5× usual Salem, 31 January: 4.2 µg/m³, 0.7× usual Salem, 1 February: 2.3 µg/m³, 0.4× usual Salem, 2 February: 2.7 µg/m³, 0.5× usual Salem, 3 February: 3.6 µg/m³, 0.6× usual Salem, 4 February: 11.3 µg/m³, 1.9× usual Salem, 5 February: 2.9 µg/m³, 0.5× usual Yakima Yakima, 26 January: 8.3 µg/m³, 0.8× usual Yakima, 27 January: 15.2 µg/m³, 1.4× usual Yakima, 28 January: 18.9 µg/m³, 1.8× usual Yakima, 29 January: 25.0 µg/m³, 2.4× usual Yakima, 30 January: 28.0 µg/m³, 2.6× usual Yakima, 31 January: 26.0 µg/m³, 2.5× usual Yakima, 1 February: 5.4 µg/m³, 0.5× usual Yakima, 2 February: 7.2 µg/m³, 0.7× usual Yakima, 3 February: 7.2 µg/m³, 0.7× usual Yakima, 4 February: 6.5 µg/m³, 0.6× usual Yakima, 5 February: 7.7 µg/m³, 0.7× usual Fresno Fresno, 26 January: 4.8 µg/m³, 0.3× usual Fresno, 27 January: 12.0 µg/m³, 0.9× usual Fresno, 28 January: 14.2 µg/m³, 1.0× usual Fresno, 29 January: 17.0 µg/m³, 1.2× usual Fresno, 30 January: 29.7 µg/m³, 2.1× usual Fresno, 31 January: 29.6 µg/m³, 2.1× usual Fresno, 1 February: 25.6 µg/m³, 1.8× usual Fresno, 2 February: 13.1 µg/m³, 0.9× usual Fresno, 3 February: 9.9 µg/m³, 0.7× usual Fresno, 4 February: 2.7 µg/m³, 0.2× usual Fresno, 5 February: 3.8 µg/m³, 0.3× usual Lewiston Lewiston, 26 January: 19.8 µg/m³, 2.4× usual Lewiston, 27 January: 18.5 µg/m³, 2.3× usual Lewiston, 28 January: 22.8 µg/m³, 2.8× usual Lewiston, 29 January: 20.3 µg/m³, 2.5× usual Lewiston, 30 January: 27.6 µg/m³, 3.4× usual Lewiston, 31 January: 12.0 µg/m³, 1.5× usual Lewiston, 1 February: 3.7 µg/m³, 0.5× usual Lewiston, 2 February: 13.8 µg/m³, 1.7× usual Lewiston, 3 February: 13.6 µg/m³, 1.7× usual Lewiston, 4 February: 12.3 µg/m³, 1.5× usual Lewiston, 5 February: 7.8 µg/m³, 1.0× usual Sunnyside Sunnyside, 26 January: 5.0 µg/m³, 0.6× usual Sunnyside, 27 January: 8.9 µg/m³, 1.1× usual Sunnyside, 28 January: 11.4 µg/m³, 1.4× usual Sunnyside, 29 January: 14.8 µg/m³, 1.8× usual Sunnyside, 30 January: 27.1 µg/m³, 3.3× usual Sunnyside, 31 January: 15.0 µg/m³, 1.9× usual Sunnyside, 1 February: 2.2 µg/m³, 0.3× usual Sunnyside, 2 February: 4.6 µg/m³, 0.6× usual Sunnyside, 3 February: 3.5 µg/m³, 0.4× usual Sunnyside, 4 February: 6.6 µg/m³, 0.8× usual Sunnyside, 5 February: 5.3 µg/m³, 0.7× usual Milwaukie Milwaukie, 26 January: 4.4 µg/m³, 0.7× usual Milwaukie, 27 January: 4.9 µg/m³, 0.8× usual Milwaukie, 28 January: 7.9 µg/m³, 1.3× usual Milwaukie, 29 January: 22.0 µg/m³, 3.7× usual Milwaukie, 30 January: 26.7 µg/m³, 4.5× usual Milwaukie, 31 January: 6.8 µg/m³, 1.1× usual Milwaukie, 1 February: 5.2 µg/m³, 0.9× usual Milwaukie, 2 February: 4.3 µg/m³, 0.7× usual Milwaukie, 3 February: 4.9 µg/m³, 0.8× usual Milwaukie, 4 February: 9.7 µg/m³, 1.6× usual Milwaukie, 5 February: 5.6 µg/m³, 0.9× usual Hillsboro Hillsboro, 26 January: 6.2 µg/m³, 0.9× usual Hillsboro, 27 January: 10.1 µg/m³, 1.5× usual Hillsboro, 28 January: 12.3 µg/m³, 1.8× usual Hillsboro, 29 January: 16.5 µg/m³, 2.4× usual Hillsboro, 30 January: 26.7 µg/m³, 3.9× usual Hillsboro, 31 January: 9.5 µg/m³, 1.4× usual Hillsboro, 1 February: 3.4 µg/m³, 0.5× usual Hillsboro, 2 February: 3.5 µg/m³, 0.5× usual Hillsboro, 3 February: 5.6 µg/m³, 0.8× usual Hillsboro, 4 February: 7.5 µg/m³, 1.1× usual Hillsboro, 5 February: 3.8 µg/m³, 0.6× usual Hanford Hanford, 26 January: 6.5 µg/m³, 0.5× usual Hanford, 27 January: 8.3 µg/m³, 0.6× usual Hanford, 28 January: 15.3 µg/m³, 1.1× usual Hanford, 29 January: 16.7 µg/m³, 1.2× usual Hanford, 30 January: 27.4 µg/m³, 2.0× usual Hanford, 31 January: 33.2 µg/m³, 2.4× usual Hanford, 1 February: 30.9 µg/m³, 2.2× usual Hanford, 2 February: 13.5 µg/m³, 1.0× usual Hanford, 3 February: 7.9 µg/m³, 0.6× usual Hanford, 4 February: 4.2 µg/m³, 0.3× usual Hanford, 5 February: 5.8 µg/m³, 0.4× usual Madera Madera, 26 January: 4.1 µg/m³, 0.4× usual Madera, 27 January: 6.9 µg/m³, 0.7× usual Madera, 28 January: 8.9 µg/m³, 0.9× usual Madera, 29 January: 11.9 µg/m³, 1.2× usual Madera, 30 January: 19.3 µg/m³, 1.9× usual Madera, 31 January: 30.6 µg/m³, 3.1× usual Madera, 1 February: 20.9 µg/m³, 2.1× usual Madera, 2 February: 8.2 µg/m³, 0.8× usual Madera, 3 February: 5.7 µg/m³, 0.6× usual Madera, 4 February: 2.3 µg/m³, 0.2× usual Madera, 5 February: 2.9 µg/m³, 0.3× usual Visalia Visalia, 26 January: 5.5 µg/m³, 0.4× usual Visalia, 27 January: 9.8 µg/m³, 0.8× usual Visalia, 28 January: 10.9 µg/m³, 0.9× usual Visalia, 29 January: 13.2 µg/m³, 1.0× usual Visalia, 30 January: 22.4 µg/m³, 1.7× usual Visalia, 31 January: 28.5 µg/m³, 2.2× usual Visalia, 1 February: 27.1 µg/m³, 2.1× usual Visalia, 2 February: 10.1 µg/m³, 0.8× usual Visalia, 3 February: 6.1 µg/m³, 0.5× usual Visalia, 4 February: 3.8 µg/m³, 0.3× usual Visalia, 5 February: 3.4 µg/m³, 0.3× usual Riverside Riverside, 26 January: 4.2 µg/m³, 0.5× usual Riverside, 27 January: 4.4 µg/m³, 0.6× usual Riverside, 28 January: 11.7 µg/m³, 1.5× usual Riverside, 29 January: 10.9 µg/m³, 1.4× usual Riverside, 30 January: 18.4 µg/m³, 2.3× usual Riverside, 31 January: 27.8 µg/m³, 3.5× usual Riverside, 1 February: 29.4 µg/m³, 3.7× usual Riverside, 2 February: 28.1 µg/m³, 3.6× usual Riverside, 3 February: 20.6 µg/m³, 2.6× usual Riverside, 4 February: 12.4 µg/m³, 1.6× usual Riverside, 5 February: 6.1 µg/m³, 0.8× usual Corcoran Corcoran, 26 January: 6.6 µg/m³, 0.5× usual Corcoran, 27 January: 4.8 µg/m³, 0.4× usual Corcoran, 28 January: 10.8 µg/m³, 0.9× usual Corcoran, 29 January: 14.6 µg/m³, 1.2× usual Corcoran, 30 January: 21.9 µg/m³, 1.8× usual Corcoran, 31 January: 27.6 µg/m³, 2.3× usual Corcoran, 1 February: 26.7 µg/m³, 2.2× usual Corcoran, 2 February: 10.8 µg/m³, 0.9× usual Corcoran, 3 February: 6.0 µg/m³, 0.5× usual Corcoran, 4 February: 3.4 µg/m³, 0.3× usual Corcoran, 5 February: 4.5 µg/m³, 0.4× usual Jurupa Valley Jurupa Valley, 26 January: 6.8 µg/m³, 0.7× usual Jurupa Valley, 27 January: 7.1 µg/m³, 0.7× usual Jurupa Valley, 28 January: 13.4 µg/m³, 1.3× usual Jurupa Valley, 29 January: 15.4 µg/m³, 1.5× usual Jurupa Valley, 30 January: 21.1 µg/m³, 2.1× usual Jurupa Valley, 31 January: 27.2 µg/m³, 2.7× usual Jurupa Valley, 1 February: 35.7 µg/m³, 3.5× usual Jurupa Valley, 2 February: 36.1 µg/m³, 3.5× usual Jurupa Valley, 3 February: 28.2 µg/m³, 2.8× usual Jurupa Valley, 4 February: 13.6 µg/m³, 1.3× usual Jurupa Valley, 5 February: 8.5 µg/m³, 0.8× usual Porterville Porterville, 26 January: 8.2 µg/m³, 0.8× usual Porterville, 27 January: 7.2 µg/m³, 0.7× usual Porterville, 28 January: 8.5 µg/m³, 0.9× usual Porterville, 29 January: 11.3 µg/m³, 1.1× usual Porterville, 30 January: 18.3 µg/m³, 1.8× usual Porterville, 31 January: 25.1 µg/m³, 2.5× usual Porterville, 1 February: 17.8 µg/m³, 1.8× usual Porterville, 2 February: 8.7 µg/m³, 0.9× usual Porterville, 3 February: 7.4 µg/m³, 0.7× usual Porterville, 4 February: 5.4 µg/m³, 0.5× usual Porterville, 5 February: 4.5 µg/m³, 0.5× usual Nogales Nogales, 26 January: 7.8 µg/m³, 0.7× usual Nogales, 27 January: 12.8 µg/m³, 1.1× usual Nogales, 28 January: 16.0 µg/m³, 1.3× usual Nogales, 29 January: 8.6 µg/m³, 0.7× usual Nogales, 30 January: 21.0 µg/m³, 1.8× usual Nogales, 31 January: 24.7 µg/m³, 2.1× usual Nogales, 1 February: 37.0 µg/m³, 3.1× usual Nogales, 2 February: 26.6 µg/m³, 2.2× usual Nogales, 3 February: 24.2 µg/m³, 2.0× usual Nogales, 4 February: 11.8 µg/m³, 1.0× usual Nogales, 5 February: 16.4 µg/m³, 1.4× usual Nogales Nogales, 26 January: 8.8 µg/m³, 0.7× usual Nogales, 27 January: 9.6 µg/m³, 0.8× usual Nogales, 28 January: 14.4 µg/m³, 1.2× usual Nogales, 29 January: 6.3 µg/m³, 0.5× usual Nogales, 30 January: 15.2 µg/m³, 1.3× usual Nogales, 31 January: 20.7 µg/m³, 1.7× usual Nogales, 1 February: 31.5 µg/m³, 2.6× usual Nogales, 2 February: 27.8 µg/m³, 2.3× usual Nogales, 3 February: 15.5 µg/m³, 1.3× usual Nogales, 4 February: 14.3 µg/m³, 1.2× usual Nogales, 5 February: 16.3 µg/m³, 1.4× usual Yuma Yuma, 26 January: 10.4 µg/m³, 1.9× usual Yuma, 27 January: 3.6 µg/m³, 0.6× usual Yuma, 28 January: 8.3 µg/m³, 1.5× usual Yuma, 29 January: 13.2 µg/m³, 2.4× usual Yuma, 30 January: 12.2 µg/m³, 2.2× usual Yuma, 31 January: 14.3 µg/m³, 2.6× usual Yuma, 1 February: 27.9 µg/m³, 5.0× usual Yuma, 2 February: 15.5 µg/m³, 2.8× usual Yuma, 3 February: 13.8 µg/m³, 2.5× usual Yuma, 4 February: 12.0 µg/m³, 2.1× usual Yuma, 5 February: 7.5 µg/m³, 1.3× usual Phoenix Phoenix, 26 January: 18.2 µg/m³, 1.7× usual Phoenix, 27 January: 12.7 µg/m³, 1.2× usual Phoenix, 28 January: 6.1 µg/m³, 0.6× usual Phoenix, 29 January: 8.7 µg/m³, 0.8× usual Phoenix, 30 January: 12.3 µg/m³, 1.1× usual Phoenix, 31 January: 22.6 µg/m³, 2.1× usual Phoenix, 1 February: 25.8 µg/m³, 2.4× usual Phoenix, 2 February: 17.0 µg/m³, 1.6× usual Phoenix, 3 February: 14.0 µg/m³, 1.3× usual Phoenix, 4 February: 9.9 µg/m³, 0.9× usual Phoenix, 5 February: 11.5 µg/m³, 1.1× usual Los Angeles Los Angeles, 26 January: 5.8 µg/m³, 0.6× usual Los Angeles, 27 January: 7.0 µg/m³, 0.7× usual Los Angeles, 28 January: 11.2 µg/m³, 1.2× usual Los Angeles, 29 January: 12.1 µg/m³, 1.3× usual Los Angeles, 30 January: 14.7 µg/m³, 1.5× usual Los Angeles, 31 January: 15.8 µg/m³, 1.7× usual Los Angeles, 1 February: 18.0 µg/m³, 1.9× usual Los Angeles, 2 February: 31.4 µg/m³, 3.3× usual Los Angeles, 3 February: 21.9 µg/m³, 2.3× usual Los Angeles, 4 February: 8.3 µg/m³, 0.9× usual Los Angeles, 5 February: 6.4 µg/m³, 0.7× usual Burbank Burbank, 26 January: 6.4 µg/m³, 0.8× usual Burbank, 27 January: 5.4 µg/m³, 0.7× usual Burbank, 28 January: 12.0 µg/m³, 1.5× usual Burbank, 29 January: 11.9 µg/m³, 1.5× usual Burbank, 30 January: 14.4 µg/m³, 1.8× usual Burbank, 31 January: 16.8 µg/m³, 2.1× usual Burbank, 1 February: 17.1 µg/m³, 2.1× usual Burbank, 2 February: 30.9 µg/m³, 3.9× usual Burbank, 3 February: 21.2 µg/m³, 2.7× usual Burbank, 4 February: 8.2 µg/m³, 1.0× usual Burbank, 5 February: 4.9 µg/m³, 0.6× usual Fontana Fontana, 26 January: 5.5 µg/m³, 0.8× usual Fontana, 27 January: 5.4 µg/m³, 0.8× usual Fontana, 28 January: 9.6 µg/m³, 1.4× usual Fontana, 29 January: 12.4 µg/m³, 1.8× usual Fontana, 30 January: 17.4 µg/m³, 2.5× usual Fontana, 31 January: 20.7 µg/m³, 3.0× usual Fontana, 1 February: 21.8 µg/m³, 3.2× usual Fontana, 2 February: 26.3 µg/m³, 3.8× usual Fontana, 3 February: 17.9 µg/m³, 2.6× usual Fontana, 4 February: 15.0 µg/m³, 2.2× usual Fontana, 5 February: 5.6 µg/m³, 0.8× usual Anaheim Anaheim, 26 January: 3.8 µg/m³, 0.5× usual Anaheim, 27 January: 5.0 µg/m³, 0.6× usual Anaheim, 28 January: 8.7 µg/m³, 1.1× usual Anaheim, 29 January: 12.1 µg/m³, 1.5× usual Anaheim, 30 January: 10.9 µg/m³, 1.3× usual Anaheim, 31 January: 18.6 µg/m³, 2.3× usual Anaheim, 1 February: 23.7 µg/m³, 2.9× usual Anaheim, 2 February: 25.1 µg/m³, 3.1× usual Anaheim, 3 February: 18.8 µg/m³, 2.3× usual Anaheim, 4 February: 6.3 µg/m³, 0.8× usual Anaheim, 5 February: 6.1 µg/m³, 0.8× usual 26 Jan 28 30 1 Feb 3 5 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
Woodburn Oregon, United States 1 29 January 5.0 7.6× Yuma Arizona, United States 1 1 February 5.6 5.0× Salem Oregon, United States 1 29 January 6.0 4.6× Milwaukie Oregon, United States 1 30 January 6.0 4.5× Parkland Washington, United States 1 28 January 6.8 4.3× Chico California, United States 2 30 January 8.1 4.1× Hillsboro Oregon, United States 1 30 January 6.8 3.9× Burbank California, United States 1 2 February 8.0 3.9× Fontana California, United States 1 2 February 6.9 3.8× Riverside California, United States 3 1 February 7.9 3.7× Grants Pass Oregon, United States 2 29 January 8.6 3.6× Jurupa Valley California, United States 3 2 February 10.2 3.5× Lewiston Idaho, United States 1 30 January 8.1 3.4× Sunnyside Washington, United States 1 30 January 8.1 3.3× Los Angeles California, United States 1 2 February 9.5 3.3× Anaheim California, United States 1 2 February 8.1 3.1× Nogales Sonora, Mexico 1 1 February 12.0 3.1× Madera California, United States 1 31 January 10.0 3.1× Yakima Washington, United States 2 30 January 10.6 2.6× Nogales Arizona, United States 1 1 February 12.0 2.6× Porterville California, United States 1 31 January 9.9 2.5× Hanford California, United States 2 31 January 13.8 2.4× Phoenix Arizona, United States 1 1 February 10.8 2.4× Corcoran California, United States 2 31 January 12.0 2.3× Visalia California, United States 2 31 January 12.8 2.2× Fresno California, United States 1 30 January 14.1 2.1×
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 Mexico
Number 31 of 106 episodes in the United States and Mexico 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 Western United States, January and February 2025 26 Bars: cities reached; colour: the level of the episode's highest daily reading. All 106 .
Use this page SmogRank, Western United States, January and February 2025: 26 cities with PM2.5 at twice their usual or more, 29 January to 2 February 2025, smogrank.com/episodes/2025-01-western-united-states-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.
