SmogRank / Episodes / United States
California, United States, January and February 2026
For 8 days, from 30 January to 6 February 2026, 19 cities in the United States had PM2.5 at least twice their usual for the time of year. The worst reading was Bakersfield, California, United States: 44.0 µg/m³ on 1 February, about 3.7× its usual 11.8.
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 1 country
Days 8 30 January to 6 February 2026
Worst day 31 January 16 cities counted
Furthest above usual 7.1× Palo Alto
Day by day
Play 31 January 16 cities at twice their usual or more
Atascadero Tulare San Luis Obispo Delano Arroyo Grande Nipomo Orcutt Hollister Lompoc Salinas Prunedale Gilroy Goleta Seaside Santa Barbara Watsonville Live Oak Manteca Santa Cruz Tracy San Jose Fillmore Oxnard Livermore Simi Valley Pleasanton Thousand Oaks Santa Clarita Agoura Galt Redwood City Lancaster San Leandro Ridgecrest Elk Grove Concord Santa Monica Burbank Oakland La Crescenta-Montrose Martinez Berkeley Folsom Arden-Arcade San Francisco Inglewood Sacramento Los Angeles Pasadena Richmond Hawthorne Vallejo Roseville Vacaville Davis Torrance Compton Carson Lomita San Rafael Lincoln Whittier Woodland Glendora Long Beach Anaheim Jurupa Valley Fontana Santa Rosa Riverside Mission Viejo Windsor Lake Elsinore Banning Temecula Indio Summerlin South Spring Valley Enterprise Florin Stockton Hanford Corcoran Huntington Beach Fresno Porterville Madera Modesto Merced Clovis Turlock Visalia Bakersfield Fremont South San Francisco Mountain View Sunnyvale Palo Alto 27 Jan 28 29 30 31 1 Feb 2 3 4 5 6 7 8 9 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
Bakersfield Bakersfield, 27 January: 44.0 µg/m³, 3.7× usual Bakersfield, 28 January: 32.3 µg/m³, 2.7× usual Bakersfield, 29 January: 24.9 µg/m³, 2.1× usual Bakersfield, 30 January: 34.3 µg/m³, 2.9× usual Bakersfield, 31 January: 43.9 µg/m³, 3.7× usual Bakersfield, 1 February: 44.0 µg/m³, 3.7× usual Bakersfield, 2 February: 35.6 µg/m³, 3.0× usual Bakersfield, 3 February: 29.1 µg/m³, 2.5× usual Bakersfield, 4 February: 34.6 µg/m³, 2.9× usual Bakersfield, 5 February: 39.8 µg/m³, 3.4× usual Bakersfield, 6 February: 35.5 µg/m³, 3.0× usual Bakersfield, 7 February: 23.0 µg/m³, 1.9× usual Bakersfield, 8 February: 25.9 µg/m³, 2.2× usual Bakersfield, 9 February: 18.1 µg/m³, 1.5× usual Modesto Modesto, 27 January: 28.4 µg/m³, 2.7× usual Modesto, 28 January: 21.2 µg/m³, 2.0× usual Modesto, 29 January: 17.2 µg/m³, 1.6× usual Modesto, 30 January: 28.5 µg/m³, 2.7× usual Modesto, 31 January: 35.9 µg/m³, 3.4× usual Modesto, 1 February: 28.3 µg/m³, 2.6× usual Modesto, 2 February: 18.3 µg/m³, 1.7× usual Modesto, 3 February: 35.5 µg/m³, 3.3× usual Modesto, 4 February: 36.9 µg/m³, 3.4× usual Modesto, 5 February: 35.9 µg/m³, 3.4× usual Modesto, 6 February: 37.3 µg/m³, 3.5× usual Modesto, 7 February: 20.5 µg/m³, 1.9× usual Modesto, 8 February: 16.5 µg/m³, 1.5× usual Modesto, 9 February: 6.2 µg/m³, 0.6× usual Fresno Fresno, 27 January: 17.3 µg/m³, 1.3× usual Fresno, 28 January: 20.9 µg/m³, 1.6× usual Fresno, 29 January: 31.5 µg/m³, 2.4× usual Fresno, 30 January: 36.7 µg/m³, 2.8× usual Fresno, 31 January: 41.0 µg/m³, 3.1× usual Fresno, 1 February: 39.6 µg/m³, 3.0× usual Fresno, 2 February: 33.7 µg/m³, 2.5× usual Fresno, 3 February: 34.1 µg/m³, 2.6× usual Fresno, 4 February: 32.9 µg/m³, 2.5× usual Fresno, 5 February: 30.3 µg/m³, 2.3× usual Fresno, 6 February: 35.0 µg/m³, 2.6× usual Fresno, 7 February: 34.0 µg/m³, 2.6× usual Fresno, 8 February: 32.2 µg/m³, 2.4× usual Fresno, 9 February: 13.3 µg/m³, 1.0× usual Visalia Visalia, 27 January: 18.3 µg/m³, 1.6× usual Visalia, 28 January: 24.8 µg/m³, 2.1× usual Visalia, 29 January: 28.3 µg/m³, 2.4× usual Visalia, 30 January: 37.2 µg/m³, 3.2× usual Visalia, 31 January: 43.0 µg/m³, 3.7× usual Visalia, 1 February: 34.2 µg/m³, 2.9× usual Visalia, 2 February: 38.6 µg/m³, 3.3× usual Visalia, 3 February: 29.8 µg/m³, 2.6× usual Visalia, 4 February: 31.1 µg/m³, 2.7× usual Visalia, 5 February: 30.1 µg/m³, 2.6× usual Visalia, 6 February: 36.1 µg/m³, 3.1× usual Visalia, 7 February: 26.2 µg/m³, 2.3× usual Visalia, 8 February: 28.7 µg/m³, 2.5× usual Visalia, 9 February: 17.6 µg/m³, 1.5× usual Clovis Clovis, 27 January: 12.0 µg/m³, 1.3× usual Clovis, 28 January: 11.7 µg/m³, 1.3× usual Clovis, 29 January: 25.3 µg/m³, 2.8× usual Clovis, 30 January: 26.7 µg/m³, 3.0× usual Clovis, 31 January: 32.1 µg/m³, 3.6× usual Clovis, 1 February: 26.9 µg/m³, 3.0× usual Clovis, 2 February: 30.9 µg/m³, 3.5× usual Clovis, 3 February: 28.3 µg/m³, 3.2× usual Clovis, 4 February: 23.7 µg/m³, 2.7× usual Clovis, 5 February: 20.3 µg/m³, 2.3× usual Clovis, 6 February: 21.9 µg/m³, 2.5× usual Clovis, 7 February: 22.3 µg/m³, 2.5× usual Clovis, 8 February: 22.2 µg/m³, 2.5× usual Clovis, 9 February: 13.0 µg/m³, 1.5× usual Hanford Hanford, 27 January: 15.8 µg/m³, 1.2× usual Hanford, 28 January: 24.3 µg/m³, 1.9× usual Hanford, 29 January: 21.0 µg/m³, 1.6× usual Hanford, 30 January: 34.1 µg/m³, 2.6× usual Hanford, 31 January: 36.2 µg/m³, 2.8× usual Hanford, 1 February: 30.6 µg/m³, 2.4× usual Hanford, 2 February: 22.3 µg/m³, 1.7× usual Hanford, 3 February: 21.9 µg/m³, 1.7× usual Hanford, 4 February: 25.4 µg/m³, 2.0× usual Hanford, 5 February: 29.0 µg/m³, 2.2× usual Hanford, 6 February: 35.8 µg/m³, 2.8× usual Hanford, 7 February: 24.0 µg/m³, 1.8× usual Hanford, 8 February: 31.3 µg/m³, 2.4× usual Hanford, 9 February: 9.5 µg/m³, 0.7× usual Porterville Porterville, 27 January: 14.4 µg/m³, 1.6× usual Porterville, 28 January: 18.8 µg/m³, 2.1× usual Porterville, 29 January: 20.4 µg/m³, 2.3× usual Porterville, 30 January: 27.5 µg/m³, 3.1× usual Porterville, 31 January: 30.8 µg/m³, 3.4× usual Porterville, 1 February: 28.9 µg/m³, 3.2× usual Porterville, 2 February: 28.0 µg/m³, 3.1× usual Porterville, 3 February: 21.5 µg/m³, 2.4× usual Porterville, 4 February: 26.0 µg/m³, 2.9× usual Porterville, 5 February: 24.3 µg/m³, 2.7× usual Porterville, 6 February: 15.9 µg/m³, 1.8× usual Porterville, 7 February: 15.4 µg/m³, 1.7× usual Porterville, 8 February: 17.8 µg/m³, 2.0× usual Porterville, 9 February: 12.8 µg/m³, 1.4× usual Stockton Stockton, 27 January: 22.9 µg/m³, 2.3× usual Stockton, 28 January: 13.0 µg/m³, 1.3× usual Stockton, 29 January: 15.5 µg/m³, 1.5× usual Stockton, 30 January: 25.9 µg/m³, 2.6× usual Stockton, 31 January: 28.0 µg/m³, 2.8× usual Stockton, 1 February: 24.0 µg/m³, 2.4× usual Stockton, 2 February: 17.2 µg/m³, 1.7× usual Stockton, 3 February: 27.2 µg/m³, 2.7× usual Stockton, 4 February: 26.7 µg/m³, 2.6× usual Stockton, 5 February: 24.8 µg/m³, 2.5× usual Stockton, 6 February: 27.0 µg/m³, 2.7× usual Stockton, 7 February: 16.8 µg/m³, 1.7× usual Stockton, 8 February: 11.6 µg/m³, 1.1× usual Stockton, 9 February: 4.6 µg/m³, 0.5× usual Madera Madera, 27 January: 15.8 µg/m³, 1.8× usual Madera, 28 January: 15.0 µg/m³, 1.7× usual Madera, 29 January: 20.8 µg/m³, 2.3× usual Madera, 30 January: 25.1 µg/m³, 2.8× usual Madera, 31 January: 26.9 µg/m³, 3.0× usual Madera, 1 February: 26.4 µg/m³, 2.9× usual Madera, 2 February: 30.2 µg/m³, 3.4× usual Madera, 3 February: 28.2 µg/m³, 3.1× usual Madera, 4 February: 23.5 µg/m³, 2.6× usual Madera, 5 February: 21.5 µg/m³, 2.4× usual Madera, 6 February: 29.9 µg/m³, 3.3× usual Madera, 7 February: 25.5 µg/m³, 2.8× usual Madera, 8 February: 22.4 µg/m³, 2.5× usual Madera, 9 February: 7.2 µg/m³, 0.8× usual Fremont Fremont, 27 January: 14.9 µg/m³, 1.4× usual Fremont, 28 January: 6.4 µg/m³, 0.6× usual Fremont, 29 January: 10.7 µg/m³, 1.0× usual Fremont, 30 January: 23.7 µg/m³, 2.2× usual Fremont, 31 January: 42.6 µg/m³, 3.9× usual Fremont, 1 February: 34.4 µg/m³, 3.1× usual Fremont, 2 February: 11.7 µg/m³, 1.1× usual Fremont, 3 February: 18.4 µg/m³, 1.7× usual Fremont, 4 February: 34.0 µg/m³, 3.1× usual Fremont, 5 February: 39.1 µg/m³, 3.6× usual Fremont, 6 February: 27.0 µg/m³, 2.5× usual Fremont, 7 February: 24.1 µg/m³, 2.2× usual Fremont, 8 February: 10.2 µg/m³, 0.9× usual Fremont, 9 February: 0.9 µg/m³, 0.1× usual Palo Alto Palo Alto, 27 January: 13.1 µg/m³, 2.6× usual Palo Alto, 28 January: 6.5 µg/m³, 1.3× usual Palo Alto, 29 January: 5.7 µg/m³, 1.1× usual Palo Alto, 30 January: 18.3 µg/m³, 3.7× usual Palo Alto, 31 January: 35.6 µg/m³, 7.1× usual Palo Alto, 1 February: 22.2 µg/m³, 4.4× usual Palo Alto, 2 February: 5.3 µg/m³, 1.1× usual Palo Alto, 3 February: 13.9 µg/m³, 2.8× usual Palo Alto, 4 February: 25.6 µg/m³, 5.1× usual Palo Alto, 5 February: 30.9 µg/m³, 6.2× usual Palo Alto, 6 February: 20.8 µg/m³, 4.2× usual Palo Alto, 7 February: 18.4 µg/m³, 3.7× usual Palo Alto, 8 February: 3.8 µg/m³, 0.8× usual Palo Alto, 9 February: 2.0 µg/m³, 0.4× usual Sunnyvale Sunnyvale, 27 January: 4.8 µg/m³, 1.0× usual Sunnyvale, 28 January: 4.5 µg/m³, 0.9× usual Sunnyvale, 29 January: 4.5 µg/m³, 0.9× usual Sunnyvale, 30 January: 19.5 µg/m³, 3.9× usual Sunnyvale, 31 January: 30.4 µg/m³, 6.1× usual Sunnyvale, 1 February: 20.8 µg/m³, 4.2× usual Sunnyvale, 2 February: 4.0 µg/m³, 0.8× usual Sunnyvale, 3 February: 16.2 µg/m³, 3.2× usual Sunnyvale, 4 February: 22.1 µg/m³, 4.4× usual Sunnyvale, 5 February: 28.4 µg/m³, 5.7× usual Sunnyvale, 6 February: 18.2 µg/m³, 3.6× usual Sunnyvale, 7 February: 22.2 µg/m³, 4.4× usual Sunnyvale, 8 February: 6.5 µg/m³, 1.3× usual Sunnyvale, 9 February: 0.1 µg/m³, 0.0× usual Florin Florin, 27 January: no reading Florin, 28 January: 16.6 µg/m³, 1.2× usual Florin, 29 January: 16.7 µg/m³, 1.2× usual Florin, 30 January: 25.4 µg/m³, 1.8× usual Florin, 31 January: 29.6 µg/m³, 2.1× usual Florin, 1 February: 24.3 µg/m³, 1.7× usual Florin, 2 February: 17.6 µg/m³, 1.2× usual Florin, 3 February: 23.5 µg/m³, 1.7× usual Florin, 4 February: no reading Florin, 5 February: 24.9 µg/m³, 1.8× usual Florin, 6 February: 24.3 µg/m³, 1.7× usual Florin, 7 February: 18.9 µg/m³, 1.3× usual Florin, 8 February: no reading Florin, 9 February: no reading Merced Merced, 27 January: 18.1 µg/m³, 2.1× usual Merced, 28 January: 17.6 µg/m³, 2.0× usual Merced, 29 January: 16.1 µg/m³, 1.8× usual Merced, 30 January: 22.7 µg/m³, 2.6× usual Merced, 31 January: 27.3 µg/m³, 3.1× usual Merced, 1 February: 23.3 µg/m³, 2.6× usual Merced, 2 February: 25.6 µg/m³, 2.9× usual Merced, 3 February: 29.6 µg/m³, 3.4× usual Merced, 4 February: 25.1 µg/m³, 2.9× usual Merced, 5 February: 24.2 µg/m³, 2.7× usual Merced, 6 February: 31.7 µg/m³, 3.6× usual Merced, 7 February: 20.8 µg/m³, 2.4× usual Merced, 8 February: 14.7 µg/m³, 1.7× usual Merced, 9 February: 5.9 µg/m³, 0.7× usual Mountain View Mountain View, 27 January: no reading Mountain View, 28 January: 4.1 µg/m³, 0.8× usual Mountain View, 29 January: 3.8 µg/m³, 0.8× usual Mountain View, 30 January: 14.1 µg/m³, 2.8× usual Mountain View, 31 January: 27.1 µg/m³, 5.4× usual Mountain View, 1 February: 13.9 µg/m³, 2.8× usual Mountain View, 2 February: 3.6 µg/m³, 0.7× usual Mountain View, 3 February: 12.6 µg/m³, 2.5× usual Mountain View, 4 February: 20.1 µg/m³, 4.0× usual Mountain View, 5 February: 23.8 µg/m³, 4.8× usual Mountain View, 6 February: 15.1 µg/m³, 3.0× usual Mountain View, 7 February: 13.8 µg/m³, 2.8× usual Mountain View, 8 February: 3.4 µg/m³, 0.7× usual Mountain View, 9 February: 1.8 µg/m³, 0.4× usual Turlock Turlock, 27 January: 17.8 µg/m³, 2.0× usual Turlock, 28 January: 14.2 µg/m³, 1.6× usual Turlock, 29 January: 10.8 µg/m³, 1.2× usual Turlock, 30 January: 18.7 µg/m³, 2.1× usual Turlock, 31 January: 26.0 µg/m³, 3.0× usual Turlock, 1 February: 22.0 µg/m³, 2.5× usual Turlock, 2 February: 18.3 µg/m³, 2.1× usual Turlock, 3 February: 25.1 µg/m³, 2.9× usual Turlock, 4 February: 27.3 µg/m³, 3.1× usual Turlock, 5 February: 24.4 µg/m³, 2.8× usual Turlock, 6 February: 32.3 µg/m³, 3.7× usual Turlock, 7 February: 18.8 µg/m³, 2.1× usual Turlock, 8 February: 13.7 µg/m³, 1.6× usual Turlock, 9 February: 2.8 µg/m³, 0.3× usual Huntington Beach Huntington Beach, 27 January: 8.7 µg/m³, 0.8× usual Huntington Beach, 28 January: 21.6 µg/m³, 1.9× usual Huntington Beach, 29 January: 19.3 µg/m³, 1.7× usual Huntington Beach, 30 January: 8.1 µg/m³, 0.7× usual Huntington Beach, 31 January: 13.9 µg/m³, 1.2× usual Huntington Beach, 1 February: 14.0 µg/m³, 1.2× usual Huntington Beach, 2 February: 14.7 µg/m³, 1.3× usual Huntington Beach, 3 February: 35.1 µg/m³, 3.1× usual Huntington Beach, 4 February: 12.3 µg/m³, 1.1× usual Huntington Beach, 5 February: 5.3 µg/m³, 0.5× usual Huntington Beach, 6 February: 9.1 µg/m³, 0.8× usual Huntington Beach, 7 February: 24.8 µg/m³, 2.2× usual Huntington Beach, 8 February: 23.0 µg/m³, 2.0× usual Huntington Beach, 9 February: 14.7 µg/m³, 1.3× usual South San Francisco South San Francisco, 27 January: 15.7 µg/m³, 2.8× usual South San Francisco, 28 January: 7.5 µg/m³, 1.3× usual South San Francisco, 29 January: 7.5 µg/m³, 1.3× usual South San Francisco, 30 January: 18.5 µg/m³, 3.2× usual South San Francisco, 31 January: 23.2 µg/m³, 4.1× usual South San Francisco, 1 February: 16.5 µg/m³, 2.9× usual South San Francisco, 2 February: 8.1 µg/m³, 1.4× usual South San Francisco, 3 February: 13.3 µg/m³, 2.3× usual South San Francisco, 4 February: 19.2 µg/m³, 3.4× usual South San Francisco, 5 February: 25.5 µg/m³, 4.5× usual South San Francisco, 6 February: 14.8 µg/m³, 2.6× usual South San Francisco, 7 February: 6.6 µg/m³, 1.2× usual South San Francisco, 8 February: 4.9 µg/m³, 0.9× usual South San Francisco, 9 February: 1.8 µg/m³, 0.3× usual Corcoran Corcoran, 27 January: 15.2 µg/m³, 1.4× usual Corcoran, 28 January: 24.8 µg/m³, 2.4× usual Corcoran, 29 January: 20.7 µg/m³, 2.0× usual Corcoran, 30 January: 24.1 µg/m³, 2.3× usual Corcoran, 31 January: 24.0 µg/m³, 2.3× usual Corcoran, 1 February: 24.2 µg/m³, 2.3× usual Corcoran, 2 February: 21.8 µg/m³, 2.1× usual Corcoran, 3 February: 22.6 µg/m³, 2.2× usual Corcoran, 4 February: 24.6 µg/m³, 2.3× usual Corcoran, 5 February: 22.2 µg/m³, 2.1× usual Corcoran, 6 February: 30.2 µg/m³, 2.9× usual Corcoran, 7 February: 24.8 µg/m³, 2.4× usual Corcoran, 8 February: 25.8 µg/m³, 2.5× usual Corcoran, 9 February: 10.1 µg/m³, 1.0× usual 27 Jan 29 31 1 Feb 2 4 6 8 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
Palo Alto California, United States 3 31 January 3.3 7.1× Sunnyvale California, United States 2 31 January 5.0 6.1× Mountain View California, United States 1 31 January 3.9 5.4× South San Francisco California, United States 1 5 February 5.7 4.5× Fremont California, United States 5 31 January 11.0 3.9× Bakersfield California, United States 8 27 January 11.8 3.7× Visalia California, United States 8 31 January 11.6 3.7× Turlock California, United States 4 6 February 8.8 3.7× Clovis California, United States 5 31 January 8.9 3.6× Merced California, United States 5 6 February 8.8 3.6× Modesto California, United States 7 6 February 10.7 3.5× Porterville California, United States 5 31 January 9.0 3.4× Madera California, United States 6 2 February 9.0 3.4× Fresno California, United States 8 31 January 13.3 3.1× Huntington Beach California, United States 1 3 February 11.4 3.1× Corcoran California, United States 1 6 February 10.5 2.9× Hanford California, United States 5 31 January 13.0 2.8× Stockton California, United States 5 31 January 10.1 2.8× Florin California, United States 1 31 January 14.2 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
Number 41 of 98 episodes in 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 California, United States, January and February 2026 19 Bars: cities reached; colour: the level of the episode's highest daily reading. All 98 .
Use this page SmogRank, California, United States, January and February 2026: 19 cities with PM2.5 at twice their usual or more, 30 January to 6 February 2026, smogrank.com/episodes/2026-01-california-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.
