SmogRank / Episodes / United States
California, United States, 30 January to 6 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 Madera Porterville Modesto Merced Clovis Turlock Visalia Bakersfield Mountain View Fremont South San Francisco 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
Visalia Visalia, 27 January: 18.3 µg/m³ Visalia, 28 January: 24.8 µg/m³ Visalia, 29 January: 28.3 µg/m³ Visalia, 30 January: 37.2 µg/m³, 3.1× its usual 11.9 Visalia, 31 January: 43.0 µg/m³, 3.7× its usual 11.6 Visalia, 1 February: 34.2 µg/m³, 3.1× its usual 11.2 Visalia, 2 February: 38.6 µg/m³, 3.4× its usual 11.2 Visalia, 3 February: 29.8 µg/m³, 2.7× its usual 11.0 Visalia, 4 February: 31.1 µg/m³, 2.9× its usual 10.9 Visalia, 5 February: 30.1 µg/m³, 2.8× its usual 10.9 Visalia, 6 February: 36.1 µg/m³, 3.3× its usual 10.8 Visalia, 7 February: 26.2 µg/m³ Visalia, 8 February: 28.7 µg/m³ Visalia, 9 February: 17.6 µg/m³ Fresno Fresno, 27 January: 17.3 µg/m³ Fresno, 28 January: 20.9 µg/m³ Fresno, 29 January: 31.5 µg/m³ Fresno, 30 January: 36.7 µg/m³, 2.8× its usual 13.3 Fresno, 31 January: 41.0 µg/m³, 3.1× its usual 13.3 Fresno, 1 February: 39.6 µg/m³, 3.0× its usual 13.3 Fresno, 2 February: 33.7 µg/m³, 2.5× its usual 13.3 Fresno, 3 February: 34.1 µg/m³, 2.6× its usual 13.1 Fresno, 4 February: 32.9 µg/m³, 2.6× its usual 12.6 Fresno, 5 February: 30.3 µg/m³, 2.4× its usual 12.6 Fresno, 6 February: 35.0 µg/m³, 2.8× its usual 12.6 Fresno, 7 February: 34.0 µg/m³ Fresno, 8 February: 32.2 µg/m³ Fresno, 9 February: 13.3 µg/m³ Bakersfield Bakersfield, 27 January: 44.0 µg/m³ Bakersfield, 28 January: 32.3 µg/m³ Bakersfield, 29 January: 24.9 µg/m³ Bakersfield, 30 January: 34.3 µg/m³, 2.9× its usual 11.9 Bakersfield, 31 January: 43.9 µg/m³, 3.7× its usual 11.9 Bakersfield, 1 February: 44.0 µg/m³, 3.7× its usual 11.8 Bakersfield, 2 February: 35.6 µg/m³, 3.0× its usual 11.8 Bakersfield, 3 February: 29.1 µg/m³, 2.5× its usual 11.8 Bakersfield, 4 February: 34.6 µg/m³, 2.9× its usual 11.9 Bakersfield, 5 February: 39.8 µg/m³, 3.3× its usual 11.9 Bakersfield, 6 February: 35.5 µg/m³, 3.0× its usual 11.8 Bakersfield, 7 February: 23.0 µg/m³ Bakersfield, 8 February: 25.9 µg/m³ Bakersfield, 9 February: 18.1 µg/m³ Hanford Hanford, 27 January: 15.8 µg/m³ Hanford, 28 January: 24.3 µg/m³ Hanford, 29 January: 21.0 µg/m³ Hanford, 30 January: 34.1 µg/m³, 2.6× its usual 13.2 Hanford, 31 January: 36.2 µg/m³, 2.8× its usual 13.0 Hanford, 1 February: 30.6 µg/m³, 2.4× its usual 12.8 Hanford, 2 February: 22.3 µg/m³ Hanford, 3 February: 21.9 µg/m³ Hanford, 4 February: 25.4 µg/m³ Hanford, 5 February: 29.0 µg/m³, 2.2× its usual 13.0 Hanford, 6 February: 35.8 µg/m³, 2.8× its usual 13.0 Hanford, 7 February: 24.0 µg/m³ Hanford, 8 February: 31.3 µg/m³ Hanford, 9 February: 9.5 µg/m³ Modesto Modesto, 27 January: 28.4 µg/m³ Modesto, 28 January: 21.2 µg/m³ Modesto, 29 January: 17.2 µg/m³ Modesto, 30 January: 28.5 µg/m³, 2.6× its usual 11.0 Modesto, 31 January: 35.9 µg/m³, 3.3× its usual 10.8 Modesto, 1 February: 28.3 µg/m³, 2.6× its usual 10.7 Modesto, 2 February: 18.3 µg/m³ Modesto, 3 February: 35.5 µg/m³, 3.3× its usual 10.9 Modesto, 4 February: 36.9 µg/m³, 3.4× its usual 10.9 Modesto, 5 February: 35.9 µg/m³, 3.4× its usual 10.7 Modesto, 6 February: 37.3 µg/m³, 3.5× its usual 10.7 Modesto, 7 February: 20.5 µg/m³ Modesto, 8 February: 16.5 µg/m³ Modesto, 9 February: 6.2 µg/m³ Porterville Porterville, 27 January: 14.4 µg/m³ Porterville, 28 January: 18.8 µg/m³ Porterville, 29 January: 20.4 µg/m³ Porterville, 30 January: 27.5 µg/m³, 3.1× its usual 9.0 Porterville, 31 January: 30.8 µg/m³, 3.4× its usual 9.0 Porterville, 1 February: 28.9 µg/m³, 3.2× its usual 9.0 Porterville, 2 February: 28.0 µg/m³, 3.1× its usual 9.0 Porterville, 3 February: 21.5 µg/m³ Porterville, 4 February: 26.0 µg/m³, 2.9× its usual 9.0 Porterville, 5 February: 24.3 µg/m³ Porterville, 6 February: 15.9 µg/m³ Porterville, 7 February: 15.4 µg/m³ Porterville, 8 February: 17.8 µg/m³ Porterville, 9 February: 12.8 µg/m³ Clovis Clovis, 27 January: 12.0 µg/m³ Clovis, 28 January: 11.7 µg/m³ Clovis, 29 January: 25.3 µg/m³ Clovis, 30 January: 26.7 µg/m³, 3.0× its usual 8.9 Clovis, 31 January: 32.1 µg/m³, 3.6× its usual 8.9 Clovis, 1 February: 26.9 µg/m³, 3.2× its usual 8.5 Clovis, 2 February: 30.9 µg/m³, 3.6× its usual 8.5 Clovis, 3 February: 28.3 µg/m³, 3.4× its usual 8.4 Clovis, 4 February: 23.7 µg/m³ Clovis, 5 February: 20.3 µg/m³ Clovis, 6 February: 21.9 µg/m³ Clovis, 7 February: 22.3 µg/m³ Clovis, 8 February: 22.2 µg/m³ Clovis, 9 February: 13.0 µg/m³ Stockton Stockton, 27 January: 22.9 µg/m³ Stockton, 28 January: 13.0 µg/m³ Stockton, 29 January: 15.5 µg/m³ Stockton, 30 January: 25.9 µg/m³, 2.6× its usual 10.1 Stockton, 31 January: 28.0 µg/m³, 2.8× its usual 10.1 Stockton, 1 February: 24.0 µg/m³ Stockton, 2 February: 17.2 µg/m³ Stockton, 3 February: 27.2 µg/m³, 2.7× its usual 10.1 Stockton, 4 February: 26.7 µg/m³, 2.6× its usual 10.1 Stockton, 5 February: 24.8 µg/m³ Stockton, 6 February: 27.0 µg/m³, 2.7× its usual 10.1 Stockton, 7 February: 16.8 µg/m³ Stockton, 8 February: 11.6 µg/m³ Stockton, 9 February: 4.6 µg/m³ Madera Madera, 27 January: 15.8 µg/m³ Madera, 28 January: 15.0 µg/m³ Madera, 29 January: 20.8 µg/m³ Madera, 30 January: 25.1 µg/m³, 2.8× its usual 9.0 Madera, 31 January: 26.9 µg/m³, 3.0× its usual 9.0 Madera, 1 February: 26.4 µg/m³, 2.9× its usual 9.0 Madera, 2 February: 30.2 µg/m³, 3.4× its usual 9.0 Madera, 3 February: 28.2 µg/m³, 3.1× its usual 9.0 Madera, 4 February: 23.5 µg/m³ Madera, 5 February: 21.5 µg/m³ Madera, 6 February: 29.9 µg/m³, 3.4× its usual 8.7 Madera, 7 February: 25.5 µg/m³ Madera, 8 February: 22.4 µg/m³ Madera, 9 February: 7.2 µg/m³ Fremont Fremont, 27 January: 14.9 µg/m³ Fremont, 28 January: 6.4 µg/m³ Fremont, 29 January: 10.7 µg/m³ Fremont, 30 January: 23.7 µg/m³ Fremont, 31 January: 42.6 µg/m³, 4.2× its usual 10.1 Fremont, 1 February: 34.4 µg/m³, 3.2× its usual 10.8 Fremont, 2 February: 11.7 µg/m³ Fremont, 3 February: 18.4 µg/m³ Fremont, 4 February: 34.0 µg/m³, 2.8× its usual 12.2 Fremont, 5 February: 39.1 µg/m³, 3.3× its usual 11.7 Fremont, 6 February: 27.0 µg/m³, 2.5× its usual 10.7 Fremont, 7 February: 24.1 µg/m³ Fremont, 8 February: 10.2 µg/m³ Fremont, 9 February: 0.9 µg/m³ Palo Alto Palo Alto, 27 January: 13.1 µg/m³ Palo Alto, 28 January: 6.5 µg/m³ Palo Alto, 29 January: 5.7 µg/m³ Palo Alto, 30 January: 18.3 µg/m³ Palo Alto, 31 January: 35.6 µg/m³, 7.1× its usual 3.3 Palo Alto, 1 February: 22.2 µg/m³ Palo Alto, 2 February: 5.3 µg/m³ Palo Alto, 3 February: 13.9 µg/m³ Palo Alto, 4 February: 25.6 µg/m³, 5.1× its usual 3.6 Palo Alto, 5 February: 30.9 µg/m³, 6.2× its usual 3.8 Palo Alto, 6 February: 20.8 µg/m³ Palo Alto, 7 February: 18.4 µg/m³ Palo Alto, 8 February: 3.8 µg/m³ Palo Alto, 9 February: 2.0 µg/m³ Sunnyvale Sunnyvale, 27 January: 6.0 µg/m³ Sunnyvale, 28 January: 4.7 µg/m³ Sunnyvale, 29 January: 4.6 µg/m³ Sunnyvale, 30 January: 19.5 µg/m³ Sunnyvale, 31 January: 30.5 µg/m³, 6.1× its usual 5.0 Sunnyvale, 1 February: 21.7 µg/m³ Sunnyvale, 2 February: 5.7 µg/m³ Sunnyvale, 3 February: 17.1 µg/m³ Sunnyvale, 4 February: 24.1 µg/m³ Sunnyvale, 5 February: 28.8 µg/m³, 5.8× its usual 3.9 Sunnyvale, 6 February: 18.7 µg/m³ Sunnyvale, 7 February: 22.4 µg/m³ Sunnyvale, 8 February: 6.9 µg/m³ Sunnyvale, 9 February: 0.4 µg/m³ Florin Florin, 27 January: no reading Florin, 28 January: 16.6 µg/m³ Florin, 29 January: 16.7 µg/m³ Florin, 30 January: 25.4 µg/m³ Florin, 31 January: 29.6 µg/m³, 2.1× its usual 14.2 Florin, 1 February: 24.3 µg/m³ Florin, 2 February: 17.6 µg/m³ Florin, 3 February: 23.5 µg/m³ Florin, 4 February: no reading Florin, 5 February: 24.9 µg/m³ Florin, 6 February: 24.3 µg/m³ Florin, 7 February: 18.9 µg/m³ Florin, 8 February: no reading Florin, 9 February: no reading Merced Merced, 27 January: 18.1 µg/m³ Merced, 28 January: 17.6 µg/m³ Merced, 29 January: 16.1 µg/m³ Merced, 30 January: 22.7 µg/m³ Merced, 31 January: 27.3 µg/m³, 2.8× its usual 9.9 Merced, 1 February: 23.3 µg/m³ Merced, 2 February: 25.6 µg/m³, 2.8× its usual 9.3 Merced, 3 February: 29.6 µg/m³, 3.2× its usual 9.2 Merced, 4 February: 25.1 µg/m³, 2.7× its usual 9.2 Merced, 5 February: 24.2 µg/m³ Merced, 6 February: 31.7 µg/m³, 3.6× its usual 8.8 Merced, 7 February: 20.8 µg/m³ Merced, 8 February: 14.7 µg/m³ Merced, 9 February: 5.9 µg/m³ Mountain View Mountain View, 27 January: no reading Mountain View, 28 January: 4.1 µg/m³ Mountain View, 29 January: 3.8 µg/m³ Mountain View, 30 January: 14.1 µg/m³ Mountain View, 31 January: 27.1 µg/m³, 3.9× its usual 6.9 Mountain View, 1 February: 13.9 µg/m³ Mountain View, 2 February: 3.6 µg/m³ Mountain View, 3 February: 12.6 µg/m³ Mountain View, 4 February: 20.1 µg/m³ Mountain View, 5 February: 23.8 µg/m³ Mountain View, 6 February: 15.1 µg/m³ Mountain View, 7 February: 13.8 µg/m³ Mountain View, 8 February: 3.4 µg/m³ Mountain View, 9 February: 1.8 µg/m³ Turlock Turlock, 27 January: 17.8 µg/m³ Turlock, 28 January: 14.2 µg/m³ Turlock, 29 January: 10.8 µg/m³ Turlock, 30 January: 18.7 µg/m³ Turlock, 31 January: 26.0 µg/m³, 2.7× its usual 9.8 Turlock, 1 February: 22.0 µg/m³ Turlock, 2 February: 18.3 µg/m³ Turlock, 3 February: 25.1 µg/m³, 2.6× its usual 9.8 Turlock, 4 February: 27.3 µg/m³, 2.8× its usual 9.8 Turlock, 5 February: 24.4 µg/m³ Turlock, 6 February: 32.3 µg/m³, 3.7× its usual 8.8 Turlock, 7 February: 18.8 µg/m³ Turlock, 8 February: 13.7 µg/m³ Turlock, 9 February: 2.8 µg/m³ Huntington Beach Huntington Beach, 27 January: 8.7 µg/m³ Huntington Beach, 28 January: 21.6 µg/m³ Huntington Beach, 29 January: 19.3 µg/m³ Huntington Beach, 30 January: 8.1 µg/m³ Huntington Beach, 31 January: 13.9 µg/m³ Huntington Beach, 1 February: 14.0 µg/m³ Huntington Beach, 2 February: 14.7 µg/m³ Huntington Beach, 3 February: 35.1 µg/m³, 3.1× its usual 11.4 Huntington Beach, 4 February: 12.3 µg/m³ Huntington Beach, 5 February: 5.3 µg/m³ Huntington Beach, 6 February: 9.1 µg/m³ Huntington Beach, 7 February: 24.8 µg/m³ Huntington Beach, 8 February: 23.0 µg/m³ Huntington Beach, 9 February: 14.7 µg/m³ South San Francisco South San Francisco, 27 January: 15.7 µg/m³ South San Francisco, 28 January: 7.5 µg/m³ South San Francisco, 29 January: 7.5 µg/m³ South San Francisco, 30 January: 18.5 µg/m³ South San Francisco, 31 January: 23.2 µg/m³ South San Francisco, 1 February: 16.5 µg/m³ South San Francisco, 2 February: 8.1 µg/m³ South San Francisco, 3 February: 13.3 µg/m³ South San Francisco, 4 February: 19.2 µg/m³ South San Francisco, 5 February: 25.5 µg/m³, 4.5× its usual 5.7 South San Francisco, 6 February: 14.8 µg/m³ South San Francisco, 7 February: 6.6 µg/m³ South San Francisco, 8 February: 4.9 µg/m³ South San Francisco, 9 February: 1.8 µg/m³ Corcoran Corcoran, 27 January: 15.2 µg/m³ Corcoran, 28 January: 24.8 µg/m³ Corcoran, 29 January: 20.7 µg/m³ Corcoran, 30 January: 24.1 µg/m³ Corcoran, 31 January: 24.0 µg/m³ Corcoran, 1 February: 24.2 µg/m³ Corcoran, 2 February: 21.8 µg/m³ Corcoran, 3 February: 22.6 µg/m³ Corcoran, 4 February: 24.6 µg/m³ Corcoran, 5 February: 22.2 µg/m³ Corcoran, 6 February: 30.2 µg/m³, 2.9× its usual 10.5 Corcoran, 7 February: 24.8 µg/m³ Corcoran, 8 February: 25.8 µg/m³ Corcoran, 9 February: 10.1 µg/m³ 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× South San Francisco California, United States 1 5 February 5.7 4.5× Fremont California, United States 5 31 January 10.1 4.2× Mountain View California, United States 1 31 January 6.9 3.9× Bakersfield California, United States 8 1 February 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, 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 the United States
Number 55 of 130 episodes in the United States since our records began, by cities reached.
Eastern United States and Canada, 25 June to 2 July 2023 280 North-eastern United States and Canada, July 2026 264 Eastern United States and Canada, May and June 2023 261 North-eastern United States and Canada, 30 July to 9 August 2025 241 Eastern United States and Canada, July 2023 240 North-eastern United States and Canada, 3 to 9 June 2025 196 Eastern United States and Canada, 14 to 19 June 2023 161 North-eastern United States and Canada, 12 to 16 July 2025 119 North-western United States and Canada, August 2023 110 North-eastern United States and Canada, 10 to 14 June 2025 104 North-western United States and Canada, 4 to 11 August 2026 99 North-eastern United States and Canada, 14 to 19 February 2026 96 California, United States, 30 January to 6 February 2026 19 Bars: cities reached; colour: the level of the episode's highest daily reading. All 130 .
Use this page SmogRank, California, United States, 30 January to 6 February 2026: 19 cities with PM2.5 at twice their usual or more, 30 January to 6 February 2026, smogrank.com/episodes/2026-01-30-california-united-states (accessed 4 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.
