SmogRank / Episodes / United States
South-western United States, December 2024 to January 2025
For 5 days, from 29 December 2024 to 2 January 2025, 36 cities in the United States and Mexico had PM2.5 at least twice their usual for the time of year. The worst reading was Phoenix, Arizona, United States: 167.0 µg/m³ on 1 January, about 10× its usual 16.6.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 36 in 2 countries
Days 5 29 December 2024 to 2 January 2025
Worst day 1 January 33 cities counted
Furthest above usual 17× Mesa
Day by day
Play 1 January 33 cities at twice their usual or more
Victorville Banning Indio Lake Elsinore Temecula Glendora Ridgecrest Lancaster La Crescenta-Montrose Poway Enterprise Summerlin South Spring Valley Santa Clarita Santa Monica Brawley Henderson Boulder City El Centro Imperial Beach Agoura Simi Valley Thousand Oaks Fillmore Bakersfield Oxnard Porterville Yuma Santa Barbara Goleta Corcoran Mesquite Hanford Orcutt Lompoc Nipomo Arroyo Grande San Luis Obispo Hurricane Atascadero Cedar City Merced Turlock Apache Junction Hollister Salinas Gilroy Prunedale Manteca Seaside Watsonville Tracy Live Oak Santa Cruz Galt San Jose Livermore Pleasanton Sunnyvale Casas Adobes Florin Arden-Arcade Palo Alto Sacramento Green Valley Redwood City San Leandro Concord Davis Martinez Oakland Berkeley Vacaville South San Francisco San Francisco Richmond San Rafael Santa Rosa Windsor Las Vegas Modesto Hawthorne Visalia Stockton Madera Clovis Nogales Torrance Inglewood Fresno Carson Los Angeles Tijuana Compton El Cajon Calexico San Diego Long Beach Fontana Vallejo Oceanside Tucson Lomita Casa Grande Marana Anaheim Burbank Riverside Chula Vista Jurupa Valley Nogales Glendale Tempe Phoenix Mesa 26 Dec 27 28 29 30 31 1 Jan 2 3 4 5 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
Jurupa Valley Jurupa Valley, 26 December: 19.4 µg/m³, 1.6× usual Jurupa Valley, 27 December: 22.0 µg/m³, 1.8× usual Jurupa Valley, 28 December: 35.6 µg/m³, 2.9× usual Jurupa Valley, 29 December: 45.5 µg/m³, 3.7× usual Jurupa Valley, 30 December: 38.7 µg/m³, 3.1× usual Jurupa Valley, 31 December: 42.6 µg/m³, 3.4× usual Jurupa Valley, 1 January: 75.4 µg/m³, 6.1× usual Jurupa Valley, 2 January: 33.1 µg/m³, 2.7× usual Jurupa Valley, 3 January: 24.7 µg/m³, 2.0× usual Jurupa Valley, 4 January: 44.1 µg/m³, 3.6× usual Jurupa Valley, 5 January: 24.4 µg/m³, 2.0× usual Riverside Riverside, 26 December: 14.3 µg/m³, 1.5× usual Riverside, 27 December: 19.4 µg/m³, 2.0× usual Riverside, 28 December: 28.6 µg/m³, 2.9× usual Riverside, 29 December: 36.9 µg/m³, 3.8× usual Riverside, 30 December: 34.9 µg/m³, 3.6× usual Riverside, 31 December: 34.9 µg/m³, 3.6× usual Riverside, 1 January: 48.5 µg/m³, 4.9× usual Riverside, 2 January: 17.6 µg/m³, 1.8× usual Riverside, 3 January: 18.5 µg/m³, 1.9× usual Riverside, 4 January: 40.5 µg/m³, 4.1× usual Riverside, 5 January: 12.7 µg/m³, 1.3× usual Fontana Fontana, 26 December: 12.2 µg/m³, 1.2× usual Fontana, 27 December: 15.6 µg/m³, 1.6× usual Fontana, 28 December: 27.3 µg/m³, 2.8× usual Fontana, 29 December: 27.3 µg/m³, 2.8× usual Fontana, 30 December: 32.6 µg/m³, 3.3× usual Fontana, 31 December: 36.5 µg/m³, 3.7× usual Fontana, 1 January: 30.5 µg/m³, 3.1× usual Fontana, 2 January: 14.0 µg/m³, 1.4× usual Fontana, 3 January: 19.7 µg/m³, 2.0× usual Fontana, 4 January: 38.7 µg/m³, 3.9× usual Fontana, 5 January: 12.4 µg/m³, 1.3× usual Anaheim Anaheim, 26 December: 13.7 µg/m³, 1.3× usual Anaheim, 27 December: 11.4 µg/m³, 1.1× usual Anaheim, 28 December: 24.5 µg/m³, 2.3× usual Anaheim, 29 December: 40.0 µg/m³, 3.7× usual Anaheim, 30 December: 23.2 µg/m³, 2.1× usual Anaheim, 31 December: 42.4 µg/m³, 3.9× usual Anaheim, 1 January: 51.0 µg/m³, 4.7× usual Anaheim, 2 January: 33.0 µg/m³, 3.1× usual Anaheim, 3 January: 22.4 µg/m³, 2.1× usual Anaheim, 4 January: 21.7 µg/m³, 2.0× usual Anaheim, 5 January: 21.5 µg/m³, 2.0× usual Burbank Burbank, 26 December: 14.9 µg/m³, 1.4× usual Burbank, 27 December: 14.7 µg/m³, 1.4× usual Burbank, 28 December: 20.7 µg/m³, 2.0× usual Burbank, 29 December: 24.2 µg/m³, 2.3× usual Burbank, 30 December: 31.5 µg/m³, 3.0× usual Burbank, 31 December: 30.9 µg/m³, 2.9× usual Burbank, 1 January: 50.1 µg/m³, 4.8× usual Burbank, 2 January: 21.1 µg/m³, 2.0× usual Burbank, 3 January: 21.4 µg/m³, 2.0× usual Burbank, 4 January: 31.3 µg/m³, 3.0× usual Burbank, 5 January: 11.6 µg/m³, 1.1× usual Los Angeles Los Angeles, 26 December: 14.7 µg/m³, 1.4× usual Los Angeles, 27 December: 12.4 µg/m³, 1.2× usual Los Angeles, 28 December: 19.5 µg/m³, 1.8× usual Los Angeles, 29 December: 21.4 µg/m³, 2.0× usual Los Angeles, 30 December: 26.3 µg/m³, 2.5× usual Los Angeles, 31 December: 31.5 µg/m³, 2.9× usual Los Angeles, 1 January: 32.7 µg/m³, 3.1× usual Los Angeles, 2 January: 20.5 µg/m³, 1.9× usual Los Angeles, 3 January: 25.6 µg/m³, 2.4× usual Los Angeles, 4 January: 29.9 µg/m³, 2.8× usual Los Angeles, 5 January: 12.7 µg/m³, 1.2× usual Compton Compton, 26 December: 20.5 µg/m³, 1.3× usual Compton, 27 December: 8.4 µg/m³, 0.5× usual Compton, 28 December: 21.7 µg/m³, 1.4× usual Compton, 29 December: 27.3 µg/m³, 1.7× usual Compton, 30 December: 23.5 µg/m³, 1.5× usual Compton, 31 December: 46.0 µg/m³, 2.9× usual Compton, 1 January: 50.9 µg/m³, 3.2× usual Compton, 2 January: 32.2 µg/m³, 2.0× usual Compton, 3 January: 22.0 µg/m³, 1.4× usual Compton, 4 January: 25.3 µg/m³, 1.6× usual Compton, 5 January: 23.7 µg/m³, 1.5× usual Phoenix Phoenix, 26 December: 16.9 µg/m³, 1.0× usual Phoenix, 27 December: 19.2 µg/m³, 1.2× usual Phoenix, 28 December: 21.2 µg/m³, 1.3× usual Phoenix, 29 December: 23.1 µg/m³, 1.4× usual Phoenix, 30 December: 22.5 µg/m³, 1.4× usual Phoenix, 31 December: 45.3 µg/m³, 2.7× usual Phoenix, 1 January: 167.0 µg/m³, 10× usual Phoenix, 2 January: 25.1 µg/m³, 1.5× usual Phoenix, 3 January: 22.1 µg/m³, 1.3× usual Phoenix, 4 January: 19.4 µg/m³, 1.2× usual Phoenix, 5 January: 19.0 µg/m³, 1.1× usual Calexico Calexico, 26 December: 14.9 µg/m³, 1.1× usual Calexico, 27 December: no reading Calexico, 28 December: no reading Calexico, 29 December: no reading Calexico, 30 December: no reading Calexico, 31 December: 44.1 µg/m³, 3.4× usual Calexico, 1 January: 37.0 µg/m³, 2.8× usual Calexico, 2 January: 12.7 µg/m³, 1.0× usual Calexico, 3 January: 18.4 µg/m³, 1.4× usual Calexico, 4 January: 22.0 µg/m³, 1.7× usual Calexico, 5 January: 8.5 µg/m³, 0.6× usual Long Beach Long Beach, 26 December: 14.2 µg/m³, 1.2× usual Long Beach, 27 December: 7.7 µg/m³, 0.6× usual Long Beach, 28 December: 16.5 µg/m³, 1.4× usual Long Beach, 29 December: 25.0 µg/m³, 2.1× usual Long Beach, 30 December: 19.9 µg/m³, 1.7× usual Long Beach, 31 December: 41.5 µg/m³, 3.5× usual Long Beach, 1 January: 43.9 µg/m³, 3.7× usual Long Beach, 2 January: 29.8 µg/m³, 2.5× usual Long Beach, 3 January: 21.8 µg/m³, 1.8× usual Long Beach, 4 January: 17.2 µg/m³, 1.4× usual Long Beach, 5 January: 23.2 µg/m³, 1.9× usual Glendale Glendale, 26 December: 13.1 µg/m³, 1.4× usual Glendale, 27 December: 12.7 µg/m³, 1.3× usual Glendale, 28 December: 15.5 µg/m³, 1.6× usual Glendale, 29 December: 16.3 µg/m³, 1.7× usual Glendale, 30 December: 14.0 µg/m³, 1.5× usual Glendale, 31 December: 40.7 µg/m³, 4.2× usual Glendale, 1 January: 72.9 µg/m³, 7.6× usual Glendale, 2 January: 14.5 µg/m³, 1.5× usual Glendale, 3 January: 14.5 µg/m³, 1.5× usual Glendale, 4 January: 14.1 µg/m³, 1.5× usual Glendale, 5 January: 14.8 µg/m³, 1.5× usual Nogales Nogales, 26 December: 15.3 µg/m³, 0.9× usual Nogales, 27 December: 20.7 µg/m³, 1.2× usual Nogales, 28 December: 22.7 µg/m³, 1.3× usual Nogales, 29 December: 21.7 µg/m³, 1.3× usual Nogales, 30 December: 23.8 µg/m³, 1.4× usual Nogales, 31 December: 40.3 µg/m³, 2.4× usual Nogales, 1 January: 118.0 µg/m³, 7.0× usual Nogales, 2 January: 25.2 µg/m³, 1.5× usual Nogales, 3 January: 23.1 µg/m³, 1.4× usual Nogales, 4 January: 17.3 µg/m³, 1.0× usual Nogales, 5 January: no reading Carson Carson, 26 December: 14.8 µg/m³, 1.1× usual Carson, 27 December: 14.4 µg/m³, 1.1× usual Carson, 28 December: 21.0 µg/m³, 1.6× usual Carson, 29 December: 22.9 µg/m³, 1.7× usual Carson, 30 December: 25.0 µg/m³, 1.9× usual Carson, 31 December: 38.8 µg/m³, 2.9× usual Carson, 1 January: 28.7 µg/m³, 2.1× usual Carson, 2 January: 28.7 µg/m³, 2.1× usual Carson, 3 January: 24.1 µg/m³, 1.8× usual Carson, 4 January: 20.6 µg/m³, 1.5× usual Carson, 5 January: 19.4 µg/m³, 1.4× usual Lomita Lomita, 26 December: 8.6 µg/m³, 1.1× usual Lomita, 27 December: 10.9 µg/m³, 1.4× usual Lomita, 28 December: 16.9 µg/m³, 2.1× usual Lomita, 29 December: 21.1 µg/m³, 2.7× usual Lomita, 30 December: 24.7 µg/m³, 3.1× usual Lomita, 31 December: 34.3 µg/m³, 4.3× usual Lomita, 1 January: 21.3 µg/m³, 2.7× usual Lomita, 2 January: 22.5 µg/m³, 2.8× usual Lomita, 3 January: 20.6 µg/m³, 2.6× usual Lomita, 4 January: 13.5 µg/m³, 1.7× usual Lomita, 5 January: 10.9 µg/m³, 1.4× usual Hawthorne Hawthorne, 26 December: 18.7 µg/m³, 1.2× usual Hawthorne, 27 December: 16.5 µg/m³, 1.1× usual Hawthorne, 28 December: 22.8 µg/m³, 1.5× usual Hawthorne, 29 December: 22.2 µg/m³, 1.5× usual Hawthorne, 30 December: 24.7 µg/m³, 1.6× usual Hawthorne, 31 December: 33.0 µg/m³, 2.2× usual Hawthorne, 1 January: 28.3 µg/m³, 1.9× usual Hawthorne, 2 January: 27.1 µg/m³, 1.8× usual Hawthorne, 3 January: 22.5 µg/m³, 1.5× usual Hawthorne, 4 January: 21.6 µg/m³, 1.4× usual Hawthorne, 5 January: 19.1 µg/m³, 1.3× usual Torrance Torrance, 26 December: 13.0 µg/m³, 1.1× usual Torrance, 27 December: 12.2 µg/m³, 1.1× usual Torrance, 28 December: 19.7 µg/m³, 1.7× usual Torrance, 29 December: 20.6 µg/m³, 1.8× usual Torrance, 30 December: 24.2 µg/m³, 2.1× usual Torrance, 31 December: 31.8 µg/m³, 2.7× usual Torrance, 1 January: 22.6 µg/m³, 1.9× usual Torrance, 2 January: 24.5 µg/m³, 2.1× usual Torrance, 3 January: 21.8 µg/m³, 1.9× usual Torrance, 4 January: 16.9 µg/m³, 1.5× usual Torrance, 5 January: 15.5 µg/m³, 1.3× usual Mesa Mesa, 26 December: 11.8 µg/m³, 1.4× usual Mesa, 27 December: 11.7 µg/m³, 1.4× usual Mesa, 28 December: 15.6 µg/m³, 1.9× usual Mesa, 29 December: 19.8 µg/m³, 2.4× usual Mesa, 30 December: 16.7 µg/m³, 2.0× usual Mesa, 31 December: 31.3 µg/m³, 3.8× usual Mesa, 1 January: 137.0 µg/m³, 17× usual Mesa, 2 January: 11.7 µg/m³, 1.4× usual Mesa, 3 January: 15.0 µg/m³, 1.8× usual Mesa, 4 January: 16.1 µg/m³, 2.0× usual Mesa, 5 January: 12.3 µg/m³, 1.5× usual Inglewood Inglewood, 26 December: 16.2 µg/m³, 1.5× usual Inglewood, 27 December: 14.4 µg/m³, 1.3× usual Inglewood, 28 December: 21.4 µg/m³, 2.0× usual Inglewood, 29 December: 21.1 µg/m³, 2.0× usual Inglewood, 30 December: 22.6 µg/m³, 2.1× usual Inglewood, 31 December: 28.9 µg/m³, 2.7× usual Inglewood, 1 January: 24.5 µg/m³, 2.3× usual Inglewood, 2 January: 20.9 µg/m³, 2.0× usual Inglewood, 3 January: 21.9 µg/m³, 2.0× usual Inglewood, 4 January: 20.3 µg/m³, 1.9× usual Inglewood, 5 January: 14.5 µg/m³, 1.4× usual Casa Grande Casa Grande, 26 December: 9.5 µg/m³, 1.4× usual Casa Grande, 27 December: 13.0 µg/m³, 1.9× usual Casa Grande, 28 December: 12.9 µg/m³, 1.9× usual Casa Grande, 29 December: 15.6 µg/m³, 2.3× usual Casa Grande, 30 December: 16.0 µg/m³, 2.3× usual Casa Grande, 31 December: 28.7 µg/m³, 4.2× usual Casa Grande, 1 January: 29.5 µg/m³, 4.3× usual Casa Grande, 2 January: 15.6 µg/m³, 2.3× usual Casa Grande, 3 January: 14.0 µg/m³, 2.0× usual Casa Grande, 4 January: 15.9 µg/m³, 2.3× usual Casa Grande, 5 January: 12.3 µg/m³, 1.8× usual Tempe Tempe, 26 December: 11.6 µg/m³, 1.3× usual Tempe, 27 December: 12.4 µg/m³, 1.4× usual Tempe, 28 December: 11.4 µg/m³, 1.3× usual Tempe, 29 December: 17.8 µg/m³, 2.1× usual Tempe, 30 December: 14.0 µg/m³, 1.6× usual Tempe, 31 December: 27.4 µg/m³, 3.2× usual Tempe, 1 January: 84.9 µg/m³, 9.9× usual Tempe, 2 January: 14.6 µg/m³, 1.7× usual Tempe, 3 January: 13.1 µg/m³, 1.5× usual Tempe, 4 January: 12.7 µg/m³, 1.5× usual Tempe, 5 January: 13.9 µg/m³, 1.6× usual Tijuana Tijuana, 26 December: 35.9 µg/m³, 1.9× usual Tijuana, 27 December: 33.4 µg/m³, 1.7× usual Tijuana, 28 December: 28.0 µg/m³, 1.4× usual Tijuana, 29 December: 35.9 µg/m³, 1.9× usual Tijuana, 30 December: 25.2 µg/m³, 1.3× usual Tijuana, 31 December: 39.6 µg/m³, 2.0× usual Tijuana, 1 January: 62.1 µg/m³, 3.2× usual Tijuana, 2 January: 39.2 µg/m³, 2.0× usual Tijuana, 3 January: 32.9 µg/m³, 1.7× usual Tijuana, 4 January: 26.3 µg/m³, 1.4× usual Tijuana, 5 January: 31.7 µg/m³, 1.6× usual Chula Vista Chula Vista, 26 December: 13.3 µg/m³, 1.5× usual Chula Vista, 27 December: 13.6 µg/m³, 1.5× usual Chula Vista, 28 December: 10.7 µg/m³, 1.2× usual Chula Vista, 29 December: 18.0 µg/m³, 2.0× usual Chula Vista, 30 December: 12.4 µg/m³, 1.4× usual Chula Vista, 31 December: 19.7 µg/m³, 2.2× usual Chula Vista, 1 January: 48.7 µg/m³, 5.5× usual Chula Vista, 2 January: 22.5 µg/m³, 2.5× usual Chula Vista, 3 January: 20.7 µg/m³, 2.3× usual Chula Vista, 4 January: 16.9 µg/m³, 1.9× usual Chula Vista, 5 January: 10.9 µg/m³, 1.2× usual Nogales Nogales, 26 December: 18.9 µg/m³, 1.1× usual Nogales, 27 December: 18.3 µg/m³, 1.1× usual Nogales, 28 December: 19.9 µg/m³, 1.2× usual Nogales, 29 December: 26.1 µg/m³, 1.5× usual Nogales, 30 December: 19.8 µg/m³, 1.2× usual Nogales, 31 December: 15.6 µg/m³, 0.9× usual Nogales, 1 January: 45.6 µg/m³, 2.7× usual Nogales, 2 January: 23.2 µg/m³, 1.3× usual Nogales, 3 January: 25.2 µg/m³, 1.5× usual Nogales, 4 January: 11.3 µg/m³, 0.7× usual Nogales, 5 January: 18.6 µg/m³, 1.1× usual Fresno Fresno, 26 December: 12.8 µg/m³, 0.8× usual Fresno, 27 December: 12.2 µg/m³, 0.8× usual Fresno, 28 December: 18.3 µg/m³, 1.2× usual Fresno, 29 December: 14.0 µg/m³, 0.9× usual Fresno, 30 December: 9.3 µg/m³, 0.6× usual Fresno, 31 December: 27.3 µg/m³, 1.8× usual Fresno, 1 January: 43.0 µg/m³, 2.8× usual Fresno, 2 January: 33.4 µg/m³, 2.2× usual Fresno, 3 January: 23.3 µg/m³, 1.5× usual Fresno, 4 January: 11.7 µg/m³, 0.8× usual Fresno, 5 January: 20.0 µg/m³, 1.3× usual Tucson Tucson, 26 December: 9.3 µg/m³, 1.2× usual Tucson, 27 December: 9.0 µg/m³, 1.1× usual Tucson, 28 December: 11.8 µg/m³, 1.5× usual Tucson, 29 December: 10.8 µg/m³, 1.4× usual Tucson, 30 December: 11.0 µg/m³, 1.4× usual Tucson, 31 December: 16.1 µg/m³, 2.0× usual Tucson, 1 January: 33.7 µg/m³, 4.3× usual Tucson, 2 January: 10.9 µg/m³, 1.4× usual Tucson, 3 January: 11.6 µg/m³, 1.5× usual Tucson, 4 January: 9.8 µg/m³, 1.2× usual Tucson, 5 January: 9.0 µg/m³, 1.1× usual El Cajon El Cajon, 26 December: 12.4 µg/m³, 1.3× usual El Cajon, 27 December: 12.0 µg/m³, 1.2× usual El Cajon, 28 December: 11.2 µg/m³, 1.2× usual El Cajon, 29 December: 16.5 µg/m³, 1.7× usual El Cajon, 30 December: 12.5 µg/m³, 1.3× usual El Cajon, 31 December: 17.6 µg/m³, 1.8× usual El Cajon, 1 January: 32.7 µg/m³, 3.4× usual El Cajon, 2 January: 16.4 µg/m³, 1.7× usual El Cajon, 3 January: 20.2 µg/m³, 2.1× usual El Cajon, 4 January: 17.2 µg/m³, 1.8× usual El Cajon, 5 January: 12.8 µg/m³, 1.3× usual San Diego San Diego, 26 December: 13.8 µg/m³, 1.5× usual San Diego, 27 December: 12.0 µg/m³, 1.3× usual San Diego, 28 December: 12.8 µg/m³, 1.4× usual San Diego, 29 December: 21.6 µg/m³, 2.4× usual San Diego, 30 December: 11.7 µg/m³, 1.3× usual San Diego, 31 December: 16.1 µg/m³, 1.8× usual San Diego, 1 January: 32.6 µg/m³, 3.6× usual San Diego, 2 January: 22.8 µg/m³, 2.5× usual San Diego, 3 January: 26.6 µg/m³, 2.9× usual San Diego, 4 January: 20.7 µg/m³, 2.3× usual San Diego, 5 January: 12.8 µg/m³, 1.4× usual Visalia Visalia, 26 December: 11.1 µg/m³, 0.8× usual Visalia, 27 December: 14.9 µg/m³, 1.1× usual Visalia, 28 December: 19.3 µg/m³, 1.4× usual Visalia, 29 December: 15.3 µg/m³, 1.1× usual Visalia, 30 December: 8.1 µg/m³, 0.6× usual Visalia, 31 December: 18.7 µg/m³, 1.3× usual Visalia, 1 January: 32.3 µg/m³, 2.3× usual Visalia, 2 January: 29.2 µg/m³, 2.1× usual Visalia, 3 January: 19.8 µg/m³, 1.4× usual Visalia, 4 January: 15.9 µg/m³, 1.1× usual Visalia, 5 January: 17.8 µg/m³, 1.3× usual Marana Marana, 26 December: 10.2 µg/m³, 1.5× usual Marana, 27 December: 10.8 µg/m³, 1.5× usual Marana, 28 December: no reading Marana, 29 December: no reading Marana, 30 December: no reading Marana, 31 December: 23.4 µg/m³, 3.3× usual Marana, 1 January: 31.3 µg/m³, 4.5× usual Marana, 2 January: 12.5 µg/m³, 1.8× usual Marana, 3 January: 12.0 µg/m³, 1.7× usual Marana, 4 January: 13.9 µg/m³, 2.0× usual Marana, 5 January: 12.8 µg/m³, 1.8× usual Vallejo Vallejo, 26 December: 6.2 µg/m³, 0.8× usual Vallejo, 27 December: 8.1 µg/m³, 1.1× usual Vallejo, 28 December: no reading Vallejo, 29 December: no reading Vallejo, 30 December: no reading Vallejo, 31 December: no reading Vallejo, 1 January: 28.7 µg/m³, 3.8× usual Vallejo, 2 January: 7.7 µg/m³, 1.0× usual Vallejo, 3 January: 10.5 µg/m³, 1.4× usual Vallejo, 4 January: 10.7 µg/m³, 1.4× usual Vallejo, 5 January: 12.6 µg/m³, 1.7× usual Madera Madera, 26 December: 10.0 µg/m³, 0.9× usual Madera, 27 December: 11.4 µg/m³, 1.0× usual Madera, 28 December: 10.1 µg/m³, 0.9× usual Madera, 29 December: 9.8 µg/m³, 0.9× usual Madera, 30 December: 6.6 µg/m³, 0.6× usual Madera, 31 December: 17.4 µg/m³, 1.5× usual Madera, 1 January: 27.8 µg/m³, 2.4× usual Madera, 2 January: 13.8 µg/m³, 1.2× usual Madera, 3 January: 19.1 µg/m³, 1.7× usual Madera, 4 January: 8.3 µg/m³, 0.7× usual Madera, 5 January: 11.3 µg/m³, 1.0× usual Oceanside Oceanside, 26 December: 10.3 µg/m³, 1.5× usual Oceanside, 27 December: 9.5 µg/m³, 1.3× usual Oceanside, 28 December: 13.5 µg/m³, 1.9× usual Oceanside, 29 December: 19.9 µg/m³, 2.8× usual Oceanside, 30 December: 12.1 µg/m³, 1.7× usual Oceanside, 31 December: 12.1 µg/m³, 1.7× usual Oceanside, 1 January: 27.6 µg/m³, 3.9× usual Oceanside, 2 January: 19.9 µg/m³, 2.8× usual Oceanside, 3 January: 17.0 µg/m³, 2.4× usual Oceanside, 4 January: 15.1 µg/m³, 2.1× usual Oceanside, 5 January: 18.3 µg/m³, 2.6× usual Stockton Stockton, 26 December: 8.7 µg/m³, 0.8× usual Stockton, 27 December: 12.3 µg/m³, 1.1× usual Stockton, 28 December: 19.5 µg/m³, 1.7× usual Stockton, 29 December: 5.9 µg/m³, 0.5× usual Stockton, 30 December: 6.1 µg/m³, 0.5× usual Stockton, 31 December: 16.9 µg/m³, 1.5× usual Stockton, 1 January: 26.6 µg/m³, 2.3× usual Stockton, 2 January: 15.8 µg/m³, 1.4× usual Stockton, 3 January: 18.6 µg/m³, 1.6× usual Stockton, 4 January: 11.8 µg/m³, 1.0× usual Stockton, 5 January: 12.7 µg/m³, 1.1× usual Las Vegas Las Vegas, 26 December: 9.0 µg/m³, 0.7× usual Las Vegas, 27 December: 12.9 µg/m³, 1.0× usual Las Vegas, 28 December: 16.9 µg/m³, 1.3× usual Las Vegas, 29 December: 16.9 µg/m³, 1.3× usual Las Vegas, 30 December: 10.1 µg/m³, 0.8× usual Las Vegas, 31 December: 15.5 µg/m³, 1.2× usual Las Vegas, 1 January: 26.2 µg/m³, 2.1× usual Las Vegas, 2 January: 14.8 µg/m³, 1.2× usual Las Vegas, 3 January: 16.7 µg/m³, 1.3× usual Las Vegas, 4 January: 5.4 µg/m³, 0.4× usual Las Vegas, 5 January: 8.8 µg/m³, 0.7× usual Modesto Modesto, 26 December: 9.4 µg/m³, 0.8× usual Modesto, 27 December: 11.1 µg/m³, 0.9× usual Modesto, 28 December: 14.4 µg/m³, 1.2× usual Modesto, 29 December: 4.7 µg/m³, 0.4× usual Modesto, 30 December: 3.2 µg/m³, 0.3× usual Modesto, 31 December: 6.6 µg/m³, 0.5× usual Modesto, 1 January: 26.0 µg/m³, 2.1× usual Modesto, 2 January: 19.1 µg/m³, 1.6× usual Modesto, 3 January: 21.1 µg/m³, 1.7× usual Modesto, 4 January: 9.1 µg/m³, 0.8× usual Modesto, 5 January: 13.2 µg/m³, 1.1× usual Clovis Clovis, 26 December: 12.0 µg/m³, 1.2× usual Clovis, 27 December: 8.9 µg/m³, 0.9× usual Clovis, 28 December: 12.7 µg/m³, 1.2× usual Clovis, 29 December: 12.0 µg/m³, 1.2× usual Clovis, 30 December: 7.3 µg/m³, 0.7× usual Clovis, 31 December: 15.0 µg/m³, 1.5× usual Clovis, 1 January: 25.7 µg/m³, 2.5× usual Clovis, 2 January: 19.8 µg/m³, 1.9× usual Clovis, 3 January: 17.4 µg/m³, 1.7× usual Clovis, 4 January: 11.1 µg/m³, 1.1× usual Clovis, 5 January: 13.2 µg/m³, 1.3× usual 26 Dec 28 30 1 Jan 3 5 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
Mesa Arizona, United States 2 1 January 8.2 17× Phoenix Arizona, United States 2 1 January 16.6 10× Tempe Arizona, United States 2 1 January 8.6 9.9× Glendale Arizona, United States 2 1 January 9.6 7.6× Nogales Arizona, United States 2 1 January 16.9 7.0× Jurupa Valley California, United States 5 1 January 12.4 6.1× Chula Vista California, United States 1 1 January 8.9 5.5× Riverside California, United States 4 1 January 9.8 4.9× Burbank California, United States 3 1 January 10.5 4.8× Anaheim California, United States 4 1 January 10.8 4.7× Marana Arizona, United States 1 1 January 7.0 4.5× Lomita California, United States 1 31 December 7.9 4.3× Casa Grande Arizona, United States 2 1 January 6.9 4.3× Tucson Arizona, United States 1 1 January 7.9 4.3× Fontana California, United States 4 4 January 9.8 3.9× Oceanside California, United States 1 1 January 7.1 3.9× Vallejo California, United States 1 1 January 7.5 3.8× Long Beach California, United States 3 1 January 12.0 3.7× San Diego California, United States 1 1 January 9.1 3.6× El Cajon California, United States 1 1 January 9.7 3.4× Calexico California, United States 2 31 December 13.1 3.4× Tijuana Baja California, Mexico 2 1 January 19.4 3.2× Compton California, United States 3 1 January 16.0 3.2× Los Angeles California, United States 3 1 January 10.7 3.1× Carson California, United States 3 31 December 13.4 2.9× Fresno California, United States 2 1 January 15.1 2.8× Torrance California, United States 1 31 December 11.6 2.7× Inglewood California, United States 1 31 December 10.7 2.7× Nogales Sonora, Mexico 1 1 January 17.2 2.7× Clovis California, United States 1 1 January 10.2 2.5× Madera California, United States 1 1 January 11.5 2.4× Stockton California, United States 1 1 January 11.5 2.3× Visalia California, United States 2 1 January 14.1 2.3× Hawthorne California, United States 2 31 December 15.2 2.2× Modesto California, United States 1 1 January 12.1 2.1× Las Vegas Nevada, United States 1 1 January 12.7 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 and Mexico
Number 25 of 142 episodes in the United States and Mexico since our records began, by cities reached.
North-eastern United States and Canada, June and July 2023 280 North-eastern United States and Canada, July 2026 264 North-eastern United States and Canada, May and June 2023 261 North-eastern United States and Canada, July and August 2025 241 North-eastern United States and Canada, July 2023 240 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 South-western United States, December 2024 to January 2025 36 Bars: cities reached; colour: the level of the episode's highest daily reading. All 142 .
Use this page SmogRank, South-western United States, December 2024 to January 2025: 36 cities with PM2.5 at twice their usual or more, 29 December 2024 to 2 January 2025, smogrank.com/episodes/2024-12-south-western-united-states (accessed 3 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.
