SmogRank / World / United States / California / October 2026

Most polluted cities in California, United States, October 2026

108 cities in California, United States ranked by their average PM2.5 so far (5 of 31 days). Worst: Mecca at 20.6 µg/m³, #90 of 2,246 cities in the world. Cleanest: Lompoc at 1.9. A city needs measurements on 70% of the days to be ranked.

Ranked by unhealthy days: the share of each city's measured days with a daily mean over 35.4 µg/m³ (US AQI 101+), Unhealthy for Sensitive Groups or worse on the US EPA's scale. Ties go to the higher average.

← Mecca 0% 0.75%0
Every city in California, United States ranked for October 2026, one column each, ranked by unhealthy days: height is the share of its measured days that were unhealthy, colour its average. Point at it to read a city; tap to open it.
  1. 1Mecca
    0%
  2. 2Hanford
    0%
  3. 3Corcoran
    0%
  4. 4Fresno
    0%
  5. 5Clovis
    0%
  6. 6Imperial Beach
    0%
  7. 6Madera
    0%
  8. 8Tularelow-cost sensors
    0%
  9. 9Jurupa Valley
    0%
  10. 10Bakersfield
    0%
  11. 10Turlock
    0%
  12. 12Merced
    0%
  13. 12San Jose
    0%
  14. 14Modesto
    0%
  15. 14Yuba City
    0%
  16. 16Cereslow-cost sensors
    0%
  17. 16Manteca
    0%
  18. 16Riverside
    0%
  19. 19Hawthornelow-cost sensors
    0%
  20. 20Compton
    0%
  21. 20Sacramento
    0%
  22. 20Arden-Arcade
    0%
  23. 23Gridley
    0%
  24. 23Los Angeles
    0%
  25. 25Whittier
    0%
  26. 26Carsonlow-cost sensors
    0%
  27. 26Delanolow-cost sensors
    0%
  28. 28San Leandro
    0%
  29. 29Florinlow-cost sensors
    0%
  30. 30Fontana
    0%
  31. 30Galt
    0%
  32. 32Inglewoodlow-cost sensors
    0%
  33. 33Long Beach
    0%
  34. 34Porterville
    0%
  35. 35Oceanside
    0%
  36. 36Los Banoslow-cost sensors
    0%
  37. 37San Diego
    0%
  38. 38Anaheim
    0%
  39. 38Redwood City
    0%
  40. 40Fremontlow-cost sensors
    0%
  41. 41Davis
    0%
  42. 42Livermore
    0%
  43. 42Lomitalow-cost sensors
    0%
  44. 42Vallejo
    0%
  45. 45Lake Elsinore
    0%
  46. 45Palo Altolow-cost sensors
    0%
  47. 47Roseville
    0%
  48. 48Lincoln
    0%
  49. 49Chula Vista
    0%
  50. 49Torrancelow-cost sensors
    0%
  51. 49Tracy
    0%
  52. 52Ben Lomond
    0%
  53. 52Prunedalelow-cost sensors
    0%
  54. 54Mission Viejo
    0%
  55. 54Sunnyvalelow-cost sensors
    0%
  56. 56Gilroy
    0%
  57. 57Santa Monicalow-cost sensors
    0%
  58. 57South San Franciscolow-cost sensors
    0%
  59. 59Burbank
    0%
  60. 60Thousand Oaks
    0%
  61. 61Chico
    0%
  62. 61King City
    0%
  63. 61Redding
    0%
  64. 64Agouralow-cost sensors
    0%
  65. 64Ukiah
    0%
  66. 64Victorville
    0%
  67. 67El Cajon
    0%
  68. 67San Rafael
    0%
  69. 69Orcutt
    0%
  70. 69Santa Clarita
    0%
  71. 71Poway
    0%
  72. 71Santa Cruz
    0%
  73. 71Seasidelow-cost sensors
    0%
  74. 74Folsom
    0%
  75. 75Paradise
    0%
  76. 76Temecula
    0%
  77. 77Calexico
    0%
  78. 78Truckee
    0%
  79. 79Fillmore
    0%
  80. 79North Auburn
    0%
  81. 79Oakland
    0%
  82. 79Oceano
    0%
  83. 79Simi Valley
    0%
  84. 84El Rio
    0%
  85. 84Goletalow-cost sensors
    0%
  86. 84San Francisco
    0%
  87. 87Red Bluff
    0%
  88. 88Crestline
    0%
  89. 88Windsorlow-cost sensors
    0%
  90. 90Sebastopol
    0%
  91. 91San Mateolow-cost sensors
    0%
  92. 92Solvang
    0%
  93. 93Brawley
    0%
  94. 94Morro Bay
    0%
  95. 95Lancaster
    0%
  96. 96Vacaville
    0%
  97. 97Indio
    0%
  98. 97Salinas
    0%
  99. 99Banning
    0%
  100. 99Glendora
    0%
  101. 99Hollister
    0%
  102. 102Atascadero
    0%
  103. 103Alpine
    0%
  104. 104Big Bear City
    0%
  105. 105Guadalupe
    0%
  106. 105Ridgecrest
    0%
  107. 107Crescent City
    0%
  108. 108Lompoc
    0%

Low-cost sensors: consumer units, counted only in cities with no government-grade monitor; they read close to reference monitors on the whole, but 15 to 25% high in humid air. How we use them.

Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales

All cities in the world, October 2026 · All cities in United States, October 2026 · California now

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SmogRank, most polluted cities in California, United States, PM2.5, October 2026 (so far), smogrank.com/us/region/california/history/2026-10 (accessed 6 Oct 2026).

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You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.