SmogRank / World / United States / California / December 2025

Most polluted cities in California, United States, December 2025

122 cities in California, United States ranked by their average PM2.5 over the 31 days. Worst: Tulare at 26.6 µg/m³, #344 of 2,960 cities in the world. Cleanest: Lompoc at 1.8. 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.

← Tulare 29% 20%0
Every city in California, United States ranked for December 2025, 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. 1Tularelow-cost sensors
    29%
  2. 2Whittier
    24%
  3. 3Delanolow-cost sensors
    23%
  4. 4Jurupa Valley
    16%
  5. 5Imperial Beach
    13%
  6. 6Compton
    10%
  7. 7Anaheim
    10%
  8. 8Calexico
    8%
  9. 9Long Beach
    7%
  10. 10Bakersfield
    6%
  11. 11Riverside
    6%
  12. 12Hawthornelow-cost sensors
    4%
  13. 13Carsonlow-cost sensors
    4%
  14. 14Los Angeles
    4%
  15. 15Mammoth Lakes
    3%
  16. 16Inglewoodlow-cost sensors
    0%
  17. 17Fresno
    0%
  18. 18Rio Vista
    0%
  19. 19Modesto
    0%
  20. 20Visalia
    0%
  21. 21Madera
    0%
  22. 22Torrancelow-cost sensors
    0%
  23. 23San Diego
    0%
  24. 24Florinlow-cost sensors
    0%
  25. 25Palo Altolow-cost sensors
    0%
  26. 26Fremontlow-cost sensors
    0%
  27. 27Santa Monicalow-cost sensors
    0%
  28. 28Merced
    0%
  29. 29Burbank
    0%
  30. 29Corcoran
    0%
  31. 31Sunnyvalelow-cost sensors
    0%
  32. 32Hanford
    0%
  33. 33Lomitalow-cost sensors
    0%
  34. 34Fontana
    0%
  35. 35Manteca
    0%
  36. 35Stockton
    0%
  37. 37Turlock
    0%
  38. 37Yreka
    0%
  39. 39South San Franciscolow-cost sensors
    0%
  40. 40El Cajon
    0%
  41. 41Oakland
    0%
  42. 42Clovis
    0%
  43. 42Arden-Arcade
    0%
  44. 44San Francisco
    0%
  45. 44Woodland
    0%
  46. 46Chula Vista
    0%
  47. 47San Jose
    0%
  48. 48Ukiah
    0%
  49. 48Redding
    0%
  50. 50Big Bear City
    0%
  51. 50Roseville
    0%
  52. 52Lincoln
    0%
  53. 53Mission Viejo
    0%
  54. 53Porterville
    0%
  55. 55Oceanside
    0%
  56. 56Sacramento
    0%
  57. 57Richmond
    0%
  58. 58Berkeley
    0%
  59. 59Galt
    0%
  60. 60Alta Sierra
    0%
  61. 61Agouralow-cost sensors
    0%
  62. 61Chico
    0%
  63. 61San Leandro
    0%
  64. 64Glendora
    0%
  65. 65North Auburn
    0%
  66. 65Poway
    0%
  67. 65Victorville
    0%
  68. 68Rancho Murieta
    0%
  69. 68Vacaville
    0%
  70. 70Martinez
    0%
  71. 71San Rafael
    0%
  72. 72Redwood City
    0%
  73. 73Concord
    0%
  74. 74Lake Elsinore
    0%
  75. 74Sebastopol
    0%
  76. 74Yuba City
    0%
  77. 77Vallejo
    0%
  78. 78Atascadero
    0%
  79. 78Davis
    0%
  80. 80Willows
    0%
  81. 81Colusa
    0%
  82. 81Indio
    0%
  83. 81Pleasanton
    0%
  84. 81Windsorlow-cost sensors
    0%
  85. 85El Rio
    0%
  86. 86Ben Lomond
    0%
  87. 86Gridley
    0%
  88. 86Santa Cruz
    0%
  89. 89Folsom
    0%
  90. 89Huron
    0%
  91. 89Santa Barbara
    0%
  92. 92El Centro
    0%
  93. 92Livermore
    0%
  94. 92Simi Valley
    0%
  95. 95South Lake Tahoe
    0%
  96. 96Brawley
    0%
  97. 96Tracy
    0%
  98. 98Santa Clarita
    0%
  99. 98Crescent City
    0%
  100. 100Thousand Oaks
    0%
  101. 100La Crescenta-Montroselow-cost sensors
    0%
  102. 102Ojai
    0%
  103. 103Goletalow-cost sensors
    0%
  104. 103San Luis Obispo
    0%
  105. 105Paradise
    0%
  106. 105Seasidelow-cost sensors
    0%
  107. 107Salinas
    0%
  108. 108Carpinteria
    0%
  109. 109Truckee
    0%
  110. 110Crestline
    0%
  111. 110Hollister
    0%
  112. 110Lancaster
    0%
  113. 110Oceano
    0%
  114. 114Guadalupe
    0%
  115. 115Banning
    0%
  116. 116Alpine
    0%
  117. 117Orcutt
    0%
  118. 118Solvang
    0%
  119. 119King City
    0%
  120. 120Fillmore
    0%
  121. 121Ridgecrest
    0%
  122. 122Lompoc
    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, December 2025 · All cities in United States, December 2025 · California now

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SmogRank, most polluted cities in California, United States, PM2.5, December 2025, smogrank.com/us/region/california/history/2025-12 (accessed 7 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.