SmogRank / Episodes / United States
Western United States, January 2025
For 7 days, from 18 to 24 January 2025, 19 cities in the United States and Mexico had PM2.5 at least twice their usual for the time of year. The worst reading was Oxnard, California, United States: 60.9 µg/m³ on 22 January, about 12× its usual 4.1.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 19 in 2 countries
Days 7 18 to 24 January 2025
Worst day 19 January 13 cities counted
Furthest above usual 12× Oxnard
Day by day
Play 19 January 13 cities at twice their usual or more
Clovis Madera Atascadero Nipomo San Luis Obispo Santa Barbara Arroyo Grande Orcutt Goleta Santa Clarita Lancaster Simi Valley Lompoc Ridgecrest Thousand Oaks Agoura Merced La Crescenta-Montrose Burbank Santa Monica Los Angeles Inglewood Torrance Glendora Lomita Turlock Hollister Long Beach Victorville Anaheim Salinas Prunedale Gilroy Fontana Seaside Watsonville Tracy Live Oak Lake Elsinore Santa Cruz San Jose Livermore Banning Sunnyvale Galt Pleasanton Temecula South Lake Tahoe Oceanside Redwood City Carson City Florin Folsom San Leandro Concord Sacramento Roseville Oakland Martinez South San Francisco Berkeley Truckee Davis Poway Lincoln San Francisco Vacaville Vallejo Indio Reno Woodland San Diego El Cajon Spanish Springs San Rafael Chula Vista Summerlin South Enterprise Spring Valley Las Vegas Santa Rosa Henderson Windsor Boulder City Brawley El Centro Calexico Ukiah Yuma Compton Bakersfield Tijuana Hawthorne Fresno Visalia Modesto Stockton Carson Hanford Porterville Arden-Arcade Jurupa Valley Riverside Corcoran Manteca Yuba City Fillmore Oxnard 15 Jan 16 17 18 19 20 21 22 23 24 25 26 27 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
Hanford Hanford, 15 January: 25.8 µg/m³, 2.0× usual Hanford, 16 January: 27.9 µg/m³, 2.1× usual Hanford, 17 January: 27.3 µg/m³, 2.1× usual Hanford, 18 January: 25.6 µg/m³, 1.9× usual Hanford, 19 January: 33.5 µg/m³, 2.5× usual Hanford, 20 January: 28.1 µg/m³, 2.1× usual Hanford, 21 January: 29.9 µg/m³, 2.3× usual Hanford, 22 January: 28.8 µg/m³, 2.2× usual Hanford, 23 January: 37.0 µg/m³, 2.8× usual Hanford, 24 January: 34.8 µg/m³, 2.6× usual Hanford, 25 January: 22.3 µg/m³, 1.7× usual Hanford, 26 January: 6.5 µg/m³, 0.5× usual Hanford, 27 January: 8.3 µg/m³, 0.6× usual Visalia Visalia, 15 January: 15.5 µg/m³, 1.1× usual Visalia, 16 January: 15.0 µg/m³, 1.1× usual Visalia, 17 January: 21.2 µg/m³, 1.6× usual Visalia, 18 January: 33.8 µg/m³, 2.5× usual Visalia, 19 January: 32.0 µg/m³, 2.4× usual Visalia, 20 January: 32.5 µg/m³, 2.4× usual Visalia, 21 January: 26.5 µg/m³, 2.0× usual Visalia, 22 January: 27.3 µg/m³, 2.0× usual Visalia, 23 January: 30.9 µg/m³, 2.3× usual Visalia, 24 January: 17.9 µg/m³, 1.3× usual Visalia, 25 January: 13.1 µg/m³, 1.0× usual Visalia, 26 January: 5.5 µg/m³, 0.4× usual Visalia, 27 January: 9.8 µg/m³, 0.7× usual Fresno Fresno, 15 January: 24.9 µg/m³, 1.8× usual Fresno, 16 January: 26.9 µg/m³, 1.9× usual Fresno, 17 January: 22.4 µg/m³, 1.6× usual Fresno, 18 January: 33.5 µg/m³, 2.4× usual Fresno, 19 January: 30.8 µg/m³, 2.2× usual Fresno, 20 January: 32.0 µg/m³, 2.3× usual Fresno, 21 January: 30.0 µg/m³, 2.1× usual Fresno, 22 January: 28.2 µg/m³, 2.0× usual Fresno, 23 January: 31.3 µg/m³, 2.2× usual Fresno, 24 January: 25.7 µg/m³, 1.8× usual Fresno, 25 January: 21.3 µg/m³, 1.5× usual Fresno, 26 January: 4.8 µg/m³, 0.3× usual Fresno, 27 January: 12.0 µg/m³, 0.9× usual Yuba City Yuba City, 15 January: 17.9 µg/m³, 2.8× usual Yuba City, 16 January: 15.2 µg/m³, 2.3× usual Yuba City, 17 January: 23.8 µg/m³, 3.7× usual Yuba City, 18 January: 26.3 µg/m³, 4.0× usual Yuba City, 19 January: 25.8 µg/m³, 4.0× usual Yuba City, 20 January: 4.3 µg/m³, 0.7× usual Yuba City, 21 January: 11.5 µg/m³, 1.8× usual Yuba City, 22 January: 16.6 µg/m³, 2.6× usual Yuba City, 23 January: 20.1 µg/m³, 3.1× usual Yuba City, 24 January: 21.9 µg/m³, 3.4× usual Yuba City, 25 January: 7.8 µg/m³, 1.2× usual Yuba City, 26 January: 3.6 µg/m³, 0.6× usual Yuba City, 27 January: 3.8 µg/m³, 0.6× usual Corcoran Corcoran, 15 January: 18.2 µg/m³, 1.6× usual Corcoran, 16 January: 20.3 µg/m³, 1.8× usual Corcoran, 17 January: 21.7 µg/m³, 2.0× usual Corcoran, 18 January: 25.3 µg/m³, 2.3× usual Corcoran, 19 January: 28.6 µg/m³, 2.6× usual Corcoran, 20 January: 22.5 µg/m³, 2.0× usual Corcoran, 21 January: 26.9 µg/m³, 2.4× usual Corcoran, 22 January: 24.0 µg/m³, 2.2× usual Corcoran, 23 January: 36.4 µg/m³, 3.3× usual Corcoran, 24 January: 30.6 µg/m³, 2.8× usual Corcoran, 25 January: 14.5 µg/m³, 1.3× usual Corcoran, 26 January: 6.6 µg/m³, 0.6× usual Corcoran, 27 January: 4.8 µg/m³, 0.4× usual Tijuana Tijuana, 15 January: 13.2 µg/m³, 0.9× usual Tijuana, 16 January: 22.8 µg/m³, 1.5× usual Tijuana, 17 January: 26.4 µg/m³, 1.7× usual Tijuana, 18 January: 23.7 µg/m³, 1.6× usual Tijuana, 19 January: 34.8 µg/m³, 2.3× usual Tijuana, 20 January: 12.3 µg/m³, 0.8× usual Tijuana, 21 January: 12.3 µg/m³, 0.8× usual Tijuana, 22 January: 14.8 µg/m³, 1.0× usual Tijuana, 23 January: 14.4 µg/m³, 1.0× usual Tijuana, 24 January: 22.2 µg/m³, 1.5× usual Tijuana, 25 January: 45.5 µg/m³, 3.0× usual Tijuana, 26 January: 6.9 µg/m³, 0.5× usual Tijuana, 27 January: 9.9 µg/m³, 0.7× usual Bakersfield Bakersfield, 15 January: 17.0 µg/m³, 1.1× usual Bakersfield, 16 January: 13.7 µg/m³, 0.9× usual Bakersfield, 17 January: 18.1 µg/m³, 1.2× usual Bakersfield, 18 January: 26.1 µg/m³, 1.8× usual Bakersfield, 19 January: 31.6 µg/m³, 2.1× usual Bakersfield, 20 January: 32.9 µg/m³, 2.2× usual Bakersfield, 21 January: 28.3 µg/m³, 1.9× usual Bakersfield, 22 January: 28.2 µg/m³, 1.9× usual Bakersfield, 23 January: 26.8 µg/m³, 1.8× usual Bakersfield, 24 January: 24.5 µg/m³, 1.6× usual Bakersfield, 25 January: 12.4 µg/m³, 0.8× usual Bakersfield, 26 January: 7.6 µg/m³, 0.5× usual Bakersfield, 27 January: 6.8 µg/m³, 0.5× usual Jurupa Valley Jurupa Valley, 15 January: 3.4 µg/m³, 0.3× usual Jurupa Valley, 16 January: 9.8 µg/m³, 0.9× usual Jurupa Valley, 17 January: 13.8 µg/m³, 1.3× usual Jurupa Valley, 18 January: 20.2 µg/m³, 1.9× usual Jurupa Valley, 19 January: 31.5 µg/m³, 3.0× usual Jurupa Valley, 20 January: 15.3 µg/m³, 1.4× usual Jurupa Valley, 21 January: 5.6 µg/m³, 0.5× usual Jurupa Valley, 22 January: 6.5 µg/m³, 0.6× usual Jurupa Valley, 23 January: 2.7 µg/m³, 0.3× usual Jurupa Valley, 24 January: 7.7 µg/m³, 0.7× usual Jurupa Valley, 25 January: 15.9 µg/m³, 1.5× usual Jurupa Valley, 26 January: 6.8 µg/m³, 0.6× usual Jurupa Valley, 27 January: 7.1 µg/m³, 0.7× usual Riverside Riverside, 15 January: 6.0 µg/m³, 0.7× usual Riverside, 16 January: 6.1 µg/m³, 0.7× usual Riverside, 17 January: 11.2 µg/m³, 1.3× usual Riverside, 18 January: 17.9 µg/m³, 2.0× usual Riverside, 19 January: 28.4 µg/m³, 3.2× usual Riverside, 20 January: 15.4 µg/m³, 1.8× usual Riverside, 21 January: 3.7 µg/m³, 0.4× usual Riverside, 22 January: 5.7 µg/m³, 0.6× usual Riverside, 23 January: 3.2 µg/m³, 0.4× usual Riverside, 24 January: 5.8 µg/m³, 0.7× usual Riverside, 25 January: 12.1 µg/m³, 1.4× usual Riverside, 26 January: 4.2 µg/m³, 0.5× usual Riverside, 27 January: 4.4 µg/m³, 0.5× usual Compton Compton, 15 January: 16.6 µg/m³, 1.2× usual Compton, 16 January: 12.0 µg/m³, 0.9× usual Compton, 17 January: 12.7 µg/m³, 0.9× usual Compton, 18 January: 21.2 µg/m³, 1.6× usual Compton, 19 January: 27.7 µg/m³, 2.0× usual Compton, 20 January: 14.4 µg/m³, 1.1× usual Compton, 21 January: 14.5 µg/m³, 1.1× usual Compton, 22 January: 12.9 µg/m³, 0.9× usual Compton, 23 January: 20.1 µg/m³, 1.5× usual Compton, 24 January: 9.3 µg/m³, 0.7× usual Compton, 25 January: 13.1 µg/m³, 1.0× usual Compton, 26 January: 5.1 µg/m³, 0.4× usual Compton, 27 January: 6.5 µg/m³, 0.5× usual Carson Carson, 15 January: 11.8 µg/m³, 1.2× usual Carson, 16 January: 9.1 µg/m³, 0.9× usual Carson, 17 January: 11.6 µg/m³, 1.1× usual Carson, 18 January: 18.7 µg/m³, 1.8× usual Carson, 19 January: 27.4 µg/m³, 2.7× usual Carson, 20 January: 15.1 µg/m³, 1.5× usual Carson, 21 January: no reading Carson, 22 January: 9.0 µg/m³, 0.9× usual Carson, 23 January: 11.5 µg/m³, 1.1× usual Carson, 24 January: 6.7 µg/m³, 0.7× usual Carson, 25 January: no reading Carson, 26 January: no reading Carson, 27 January: no reading Porterville Porterville, 15 January: 9.3 µg/m³, 0.9× usual Porterville, 16 January: 7.6 µg/m³, 0.8× usual Porterville, 17 January: 14.7 µg/m³, 1.5× usual Porterville, 18 January: 21.1 µg/m³, 2.1× usual Porterville, 19 January: 27.3 µg/m³, 2.7× usual Porterville, 20 January: 28.6 µg/m³, 2.9× usual Porterville, 21 January: 23.0 µg/m³, 2.3× usual Porterville, 22 January: 22.6 µg/m³, 2.3× usual Porterville, 23 January: 21.5 µg/m³, 2.2× usual Porterville, 24 January: 11.1 µg/m³, 1.1× usual Porterville, 25 January: 8.7 µg/m³, 0.9× usual Porterville, 26 January: 8.2 µg/m³, 0.8× usual Porterville, 27 January: 7.2 µg/m³, 0.7× usual Hawthorne Hawthorne, 15 January: 13.6 µg/m³, 1.2× usual Hawthorne, 16 January: 10.9 µg/m³, 1.0× usual Hawthorne, 17 January: 13.5 µg/m³, 1.2× usual Hawthorne, 18 January: 20.2 µg/m³, 1.8× usual Hawthorne, 19 January: 26.8 µg/m³, 2.4× usual Hawthorne, 20 January: 16.3 µg/m³, 1.4× usual Hawthorne, 21 January: no reading Hawthorne, 22 January: 10.1 µg/m³, 0.9× usual Hawthorne, 23 January: 13.8 µg/m³, 1.2× usual Hawthorne, 24 January: 6.9 µg/m³, 0.6× usual Hawthorne, 25 January: no reading Hawthorne, 26 January: no reading Hawthorne, 27 January: no reading Oxnard Oxnard, 15 January: 1.8 µg/m³, 0.4× usual Oxnard, 16 January: 2.8 µg/m³, 0.6× usual Oxnard, 17 January: 5.5 µg/m³, 1.1× usual Oxnard, 18 January: 7.5 µg/m³, 1.5× usual Oxnard, 19 January: 7.6 µg/m³, 1.5× usual Oxnard, 20 January: 8.7 µg/m³, 1.7× usual Oxnard, 21 January: 2.3 µg/m³, 0.5× usual Oxnard, 22 January: 60.9 µg/m³, 12× usual Oxnard, 23 January: 5.6 µg/m³, 1.1× usual Oxnard, 24 January: 3.2 µg/m³, 0.6× usual Oxnard, 25 January: 5.4 µg/m³, 1.1× usual Oxnard, 26 January: 3.3 µg/m³, 0.7× usual Oxnard, 27 January: 2.0 µg/m³, 0.4× usual Fillmore Fillmore, 15 January: no reading Fillmore, 16 January: 3.1 µg/m³, 0.6× usual Fillmore, 17 January: no reading Fillmore, 18 January: no reading Fillmore, 19 January: no reading Fillmore, 20 January: no reading Fillmore, 21 January: 2.4 µg/m³, 0.5× usual Fillmore, 22 January: 52.2 µg/m³, 10× usual Fillmore, 23 January: no reading Fillmore, 24 January: no reading Fillmore, 25 January: 6.5 µg/m³, 1.3× usual Fillmore, 26 January: 2.8 µg/m³, 0.6× usual Fillmore, 27 January: 2.3 µg/m³, 0.5× usual Stockton Stockton, 15 January: no reading Stockton, 16 January: no reading Stockton, 17 January: no reading Stockton, 18 January: 20.0 µg/m³, 1.8× usual Stockton, 19 January: 23.8 µg/m³, 2.2× usual Stockton, 20 January: 13.1 µg/m³, 1.2× usual Stockton, 21 January: 21.2 µg/m³, 1.9× usual Stockton, 22 January: 23.3 µg/m³, 2.1× usual Stockton, 23 January: 29.2 µg/m³, 2.7× usual Stockton, 24 January: 27.5 µg/m³, 2.5× usual Stockton, 25 January: 21.7 µg/m³, 2.0× usual Stockton, 26 January: 6.0 µg/m³, 0.5× usual Stockton, 27 January: 8.7 µg/m³, 0.8× usual Manteca Manteca, 15 January: 23.0 µg/m³, 2.8× usual Manteca, 16 January: 20.6 µg/m³, 2.5× usual Manteca, 17 January: 18.8 µg/m³, 2.3× usual Manteca, 18 January: 14.0 µg/m³, 1.7× usual Manteca, 19 January: 24.1 µg/m³, 2.9× usual Manteca, 20 January: 9.0 µg/m³, 1.1× usual Manteca, 21 January: 17.0 µg/m³, 2.0× usual Manteca, 22 January: 16.1 µg/m³, 1.9× usual Manteca, 23 January: 23.5 µg/m³, 2.8× usual Manteca, 24 January: 29.5 µg/m³, 3.6× usual Manteca, 25 January: 16.5 µg/m³, 2.0× usual Manteca, 26 January: 7.5 µg/m³, 0.9× usual Manteca, 27 January: 7.9 µg/m³, 1.0× usual Modesto Modesto, 15 January: 18.3 µg/m³, 1.7× usual Modesto, 16 January: 21.6 µg/m³, 2.0× usual Modesto, 17 January: 20.8 µg/m³, 1.9× usual Modesto, 18 January: 17.2 µg/m³, 1.6× usual Modesto, 19 January: 23.0 µg/m³, 2.1× usual Modesto, 20 January: 12.7 µg/m³, 1.2× usual Modesto, 21 January: 16.4 µg/m³, 1.5× usual Modesto, 22 January: 19.0 µg/m³, 1.7× usual Modesto, 23 January: 24.3 µg/m³, 2.2× usual Modesto, 24 January: 27.8 µg/m³, 2.6× usual Modesto, 25 January: 14.3 µg/m³, 1.3× usual Modesto, 26 January: 5.6 µg/m³, 0.5× usual Modesto, 27 January: 7.6 µg/m³, 0.7× usual Arden-Arcade Arden-Arcade, 15 January: 17.4 µg/m³, 2.1× usual Arden-Arcade, 16 January: 15.1 µg/m³, 1.8× usual Arden-Arcade, 17 January: 18.3 µg/m³, 2.2× usual Arden-Arcade, 18 January: 22.0 µg/m³, 2.7× usual Arden-Arcade, 19 January: 24.2 µg/m³, 2.9× usual Arden-Arcade, 20 January: 15.8 µg/m³, 1.9× usual Arden-Arcade, 21 January: 12.5 µg/m³, 1.5× usual Arden-Arcade, 22 January: 16.6 µg/m³, 2.0× usual Arden-Arcade, 23 January: 20.7 µg/m³, 2.5× usual Arden-Arcade, 24 January: 25.0 µg/m³, 3.0× usual Arden-Arcade, 25 January: 19.1 µg/m³, 2.3× usual Arden-Arcade, 26 January: 8.0 µg/m³, 1.0× usual Arden-Arcade, 27 January: 7.4 µg/m³, 0.9× usual 15 Jan 17 19 21 23 25 27 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
Oxnard California, United States 1 22 January 4.1 12× Fillmore California, United States 1 22 January 2.7 10× Yuba City California, United States 2 18 January 6.5 4.0× Manteca California, United States 1 24 January 8.3 3.6× Corcoran California, United States 5 23 January 11.1 3.3× Riverside California, United States 1 19 January 8.8 3.2× Tijuana Baja California, Mexico 1 25 January 15.1 3.0× Arden-Arcade California, United States 1 24 January 8.3 3.0× Jurupa Valley California, United States 1 19 January 10.6 3.0× Porterville California, United States 2 20 January 10.0 2.9× Hanford California, United States 6 23 January 13.2 2.8× Carson California, United States 1 19 January 10.2 2.7× Stockton California, United States 2 23 January 11.0 2.7× Modesto California, United States 1 24 January 10.9 2.6× Visalia California, United States 5 18 January 13.5 2.5× Fresno California, United States 6 18 January 14.0 2.4× Hawthorne California, United States 1 19 January 11.3 2.4× Bakersfield California, United States 5 20 January 14.9 2.2× Compton California, United States 1 19 January 13.6 2.0×
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 44 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 2025 19 Bars: cities reached; colour: the level of the episode's highest daily reading. All 106 .
Use this page SmogRank, Western United States, January 2025: 19 cities with PM2.5 at twice their usual or more, 18 to 24 January 2025, smogrank.com/episodes/2025-01-western-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.
