SmogRank / Episodes / United States
Western United States, January 2026
For 3 days, from 21 to 23 January 2026, 19 cities in the United States and Mexico had PM2.5 at least twice their usual for the time of year. The worst reading was Riverside, California, United States: 54.2 µg/m³ on 22 January, about 6.9× its usual 7.9.
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 2 countries
Days 3 21 to 23 January 2026
Worst day 21 January 15 cities counted
Furthest above usual 8.6× Pasadena
Day by day
Play 21 January 15 cities at twice their usual or more
Mission Viejo Oceanside Lake Elsinore Temecula Poway El Cajon Chula Vista Burbank La Crescenta-Montrose Banning Agoura Santa Clarita Thousand Oaks Simi Valley Lancaster Indio Fillmore Oxnard Santa Barbara Brawley El Centro Ridgecrest Calexico Goleta Mexicali Bakersfield Delano Lompoc Orcutt Yuma Nipomo Arroyo Grande San Luis Obispo Atascadero Hawthorne Compton Tijuana Los Angeles Carson Torrance Long Beach San Diego Inglewood Lomita Anaheim Whittier Santa Monica Jurupa Valley Huntington Beach Fontana Riverside Glendora Pasadena 18 Jan 19 20 21 22 23 24 25 26 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
Huntington Beach Huntington Beach, 18 January: 24.0 µg/m³, 2.7× usual Huntington Beach, 19 January: 19.1 µg/m³, 2.1× usual Huntington Beach, 20 January: 30.8 µg/m³, 3.5× usual Huntington Beach, 21 January: 50.9 µg/m³, 5.7× usual Huntington Beach, 22 January: 40.7 µg/m³, 4.6× usual Huntington Beach, 23 January: 21.1 µg/m³, 2.4× usual Huntington Beach, 24 January: 7.6 µg/m³, 0.9× usual Huntington Beach, 25 January: 18.8 µg/m³, 2.1× usual Huntington Beach, 26 January: 14.3 µg/m³, 1.6× usual Hawthorne Hawthorne, 18 January: 11.0 µg/m³, 1.0× usual Hawthorne, 19 January: 20.6 µg/m³, 1.9× usual Hawthorne, 20 January: 27.5 µg/m³, 2.5× usual Hawthorne, 21 January: 26.9 µg/m³, 2.4× usual Hawthorne, 22 January: 20.0 µg/m³, 1.8× usual Hawthorne, 23 January: 16.0 µg/m³, 1.5× usual Hawthorne, 24 January: 7.9 µg/m³, 0.7× usual Hawthorne, 25 January: 15.6 µg/m³, 1.4× usual Hawthorne, 26 January: 11.6 µg/m³, 1.1× usual Whittier Whittier, 18 January: 13.6 µg/m³, 1.2× usual Whittier, 19 January: 22.0 µg/m³, 2.0× usual Whittier, 20 January: 20.2 µg/m³, 1.8× usual Whittier, 21 January: 49.4 µg/m³, 4.5× usual Whittier, 22 January: 46.2 µg/m³, 4.2× usual Whittier, 23 January: 18.9 µg/m³, 1.7× usual Whittier, 24 January: 13.6 µg/m³, 1.2× usual Whittier, 25 January: 27.1 µg/m³, 2.4× usual Whittier, 26 January: 7.2 µg/m³, 0.6× usual Tijuana Tijuana, 18 January: 15.0 µg/m³, 1.0× usual Tijuana, 19 January: 26.3 µg/m³, 1.8× usual Tijuana, 20 January: 25.4 µg/m³, 1.8× usual Tijuana, 21 January: 33.8 µg/m³, 2.4× usual Tijuana, 22 January: 35.1 µg/m³, 2.5× usual Tijuana, 23 January: 15.0 µg/m³, 1.0× usual Tijuana, 24 January: 7.2 µg/m³, 0.5× usual Tijuana, 25 January: 17.9 µg/m³, 1.3× usual Tijuana, 26 January: 10.9 µg/m³, 0.8× usual Anaheim Anaheim, 18 January: 10.7 µg/m³, 1.4× usual Anaheim, 19 January: 12.4 µg/m³, 1.6× usual Anaheim, 20 January: 16.2 µg/m³, 2.1× usual Anaheim, 21 January: 33.4 µg/m³, 4.4× usual Anaheim, 22 January: 30.8 µg/m³, 4.1× usual Anaheim, 23 January: 16.1 µg/m³, 2.1× usual Anaheim, 24 January: 8.6 µg/m³, 1.1× usual Anaheim, 25 January: 10.6 µg/m³, 1.4× usual Anaheim, 26 January: 8.1 µg/m³, 1.1× usual Compton Compton, 18 January: 13.0 µg/m³, 1.0× usual Compton, 19 January: 18.1 µg/m³, 1.4× usual Compton, 20 January: 17.4 µg/m³, 1.3× usual Compton, 21 January: 32.0 µg/m³, 2.4× usual Compton, 22 January: 18.1 µg/m³, 1.4× usual Compton, 23 January: 10.6 µg/m³, 0.8× usual Compton, 24 January: 11.2 µg/m³, 0.8× usual Compton, 25 January: 17.0 µg/m³, 1.3× usual Compton, 26 January: 12.2 µg/m³, 0.9× usual Inglewood Inglewood, 18 January: 5.5 µg/m³, 0.7× usual Inglewood, 19 January: 17.5 µg/m³, 2.3× usual Inglewood, 20 January: 18.3 µg/m³, 2.4× usual Inglewood, 21 January: 29.3 µg/m³, 3.9× usual Inglewood, 22 January: 20.2 µg/m³, 2.7× usual Inglewood, 23 January: 16.8 µg/m³, 2.2× usual Inglewood, 24 January: 7.4 µg/m³, 1.0× usual Inglewood, 25 January: 11.9 µg/m³, 1.6× usual Inglewood, 26 January: 9.2 µg/m³, 1.2× usual Long Beach Long Beach, 18 January: 9.7 µg/m³, 1.1× usual Long Beach, 19 January: 14.1 µg/m³, 1.6× usual Long Beach, 20 January: 19.7 µg/m³, 2.2× usual Long Beach, 21 January: 28.2 µg/m³, 3.1× usual Long Beach, 22 January: 14.2 µg/m³, 1.6× usual Long Beach, 23 January: 9.8 µg/m³, 1.1× usual Long Beach, 24 January: 8.0 µg/m³, 0.9× usual Long Beach, 25 January: 13.3 µg/m³, 1.5× usual Long Beach, 26 January: 12.5 µg/m³, 1.4× usual Carson Carson, 18 January: 9.0 µg/m³, 0.9× usual Carson, 19 January: 16.3 µg/m³, 1.7× usual Carson, 20 January: 24.9 µg/m³, 2.5× usual Carson, 21 January: 27.9 µg/m³, 2.8× usual Carson, 22 January: 20.4 µg/m³, 2.1× usual Carson, 23 January: 14.4 µg/m³, 1.5× usual Carson, 24 January: 6.7 µg/m³, 0.7× usual Carson, 25 January: 13.2 µg/m³, 1.3× usual Carson, 26 January: 11.1 µg/m³, 1.1× usual Pasadena Pasadena, 18 January: 1.1 µg/m³, 0.2× usual Pasadena, 19 January: 4.2 µg/m³, 0.8× usual Pasadena, 20 January: 1.0 µg/m³, 0.2× usual Pasadena, 21 January: 27.1 µg/m³, 5.4× usual Pasadena, 22 January: 43.1 µg/m³, 8.6× usual Pasadena, 23 January: 38.3 µg/m³, 7.7× usual Pasadena, 24 January: 20.1 µg/m³, 4.0× usual Pasadena, 25 January: 3.1 µg/m³, 0.6× usual Pasadena, 26 January: 0.3 µg/m³, 0.1× usual Torrance Torrance, 18 January: 7.5 µg/m³, 0.9× usual Torrance, 19 January: 16.6 µg/m³, 1.9× usual Torrance, 20 January: 22.2 µg/m³, 2.6× usual Torrance, 21 January: 26.1 µg/m³, 3.0× usual Torrance, 22 January: 18.9 µg/m³, 2.2× usual Torrance, 23 January: 12.5 µg/m³, 1.5× usual Torrance, 24 January: 6.0 µg/m³, 0.7× usual Torrance, 25 January: 11.6 µg/m³, 1.3× usual Torrance, 26 January: 9.0 µg/m³, 1.0× usual Los Angeles Los Angeles, 18 January: 7.4 µg/m³, 0.8× usual Los Angeles, 19 January: 14.8 µg/m³, 1.6× usual Los Angeles, 20 January: 11.5 µg/m³, 1.2× usual Los Angeles, 21 January: 26.1 µg/m³, 2.7× usual Los Angeles, 22 January: 16.4 µg/m³, 1.7× usual Los Angeles, 23 January: 13.2 µg/m³, 1.4× usual Los Angeles, 24 January: 8.9 µg/m³, 0.9× usual Los Angeles, 25 January: 8.8 µg/m³, 0.9× usual Los Angeles, 26 January: 7.2 µg/m³, 0.8× usual Lomita Lomita, 18 January: 5.2 µg/m³, 0.8× usual Lomita, 19 January: 9.0 µg/m³, 1.4× usual Lomita, 20 January: 14.6 µg/m³, 2.3× usual Lomita, 21 January: 25.5 µg/m³, 4.0× usual Lomita, 22 January: 17.5 µg/m³, 2.7× usual Lomita, 23 January: 9.6 µg/m³, 1.5× usual Lomita, 24 January: 6.1 µg/m³, 1.0× usual Lomita, 25 January: 8.4 µg/m³, 1.3× usual Lomita, 26 January: 7.0 µg/m³, 1.1× usual San Diego San Diego, 18 January: 7.6 µg/m³, 1.0× usual San Diego, 19 January: 9.5 µg/m³, 1.2× usual San Diego, 20 January: 18.0 µg/m³, 2.3× usual San Diego, 21 January: 25.3 µg/m³, 3.2× usual San Diego, 22 January: 24.0 µg/m³, 3.0× usual San Diego, 23 January: 14.2 µg/m³, 1.8× usual San Diego, 24 January: 6.9 µg/m³, 0.9× usual San Diego, 25 January: 8.6 µg/m³, 1.1× usual San Diego, 26 January: 6.2 µg/m³, 0.8× usual Santa Monica Santa Monica, 18 January: 4.1 µg/m³, 0.8× usual Santa Monica, 19 January: 10.8 µg/m³, 2.0× usual Santa Monica, 20 January: 11.0 µg/m³, 2.1× usual Santa Monica, 21 January: 25.2 µg/m³, 4.8× usual Santa Monica, 22 January: 19.4 µg/m³, 3.7× usual Santa Monica, 23 January: 15.2 µg/m³, 2.9× usual Santa Monica, 24 January: 6.6 µg/m³, 1.2× usual Santa Monica, 25 January: 5.9 µg/m³, 1.1× usual Santa Monica, 26 January: 5.1 µg/m³, 1.0× usual Riverside Riverside, 18 January: 9.4 µg/m³, 1.2× usual Riverside, 19 January: 10.2 µg/m³, 1.3× usual Riverside, 20 January: 11.1 µg/m³, 1.4× usual Riverside, 21 January: 23.5 µg/m³, 3.0× usual Riverside, 22 January: 54.2 µg/m³, 6.9× usual Riverside, 23 January: 41.1 µg/m³, 5.2× usual Riverside, 24 January: 16.2 µg/m³, 2.1× usual Riverside, 25 January: 13.5 µg/m³, 1.7× usual Riverside, 26 January: 9.1 µg/m³, 1.2× usual Jurupa Valley Jurupa Valley, 18 January: 17.5 µg/m³, 1.8× usual Jurupa Valley, 19 January: 18.9 µg/m³, 1.9× usual Jurupa Valley, 20 January: 13.6 µg/m³, 1.4× usual Jurupa Valley, 21 January: 24.0 µg/m³, 2.4× usual Jurupa Valley, 22 January: 48.5 µg/m³, 4.9× usual Jurupa Valley, 23 January: 30.3 µg/m³, 3.1× usual Jurupa Valley, 24 January: 13.8 µg/m³, 1.4× usual Jurupa Valley, 25 January: 16.0 µg/m³, 1.6× usual Jurupa Valley, 26 January: 12.3 µg/m³, 1.3× usual Fontana Fontana, 18 January: 8.3 µg/m³, 1.1× usual Fontana, 19 January: 10.4 µg/m³, 1.4× usual Fontana, 20 January: 11.0 µg/m³, 1.5× usual Fontana, 21 January: 19.4 µg/m³, 2.7× usual Fontana, 22 January: 44.7 µg/m³, 6.1× usual Fontana, 23 January: 30.2 µg/m³, 4.1× usual Fontana, 24 January: 10.3 µg/m³, 1.4× usual Fontana, 25 January: 6.9 µg/m³, 0.9× usual Fontana, 26 January: 6.8 µg/m³, 0.9× usual Glendora Glendora, 18 January: 2.3 µg/m³, 0.5× usual Glendora, 19 January: 4.2 µg/m³, 0.8× usual Glendora, 20 January: 2.7 µg/m³, 0.5× usual Glendora, 21 January: 20.7 µg/m³, 4.1× usual Glendora, 22 January: 34.3 µg/m³, 6.9× usual Glendora, 23 January: 18.6 µg/m³, 3.7× usual Glendora, 24 January: 8.2 µg/m³, 1.6× usual Glendora, 25 January: 4.1 µg/m³, 0.8× usual Glendora, 26 January: 3.4 µg/m³, 0.7× usual 18 Jan 19 20 21 22 23 24 25 26 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
Pasadena California, United States 3 22 January 2.5 8.6× Riverside California, United States 2 22 January 7.9 6.9× Glendora California, United States 1 22 January 4.5 6.9× Fontana California, United States 2 22 January 7.3 6.1× Huntington Beach California, United States 2 21 January 8.9 5.7× Jurupa Valley California, United States 2 22 January 9.8 4.9× Santa Monica California, United States 1 21 January 5.3 4.8× Whittier California, United States 2 21 January 11.1 4.5× Anaheim California, United States 2 21 January 7.6 4.4× Lomita California, United States 1 21 January 6.4 4.0× Inglewood California, United States 1 21 January 7.5 3.9× San Diego California, United States 1 21 January 7.9 3.2× Long Beach California, United States 1 21 January 9.0 3.1× Torrance California, United States 1 21 January 8.6 3.0× Carson California, United States 1 21 January 9.8 2.8× Los Angeles California, United States 1 21 January 9.5 2.7× Hawthorne California, United States 1 20 January 11.0 2.5× Tijuana Baja California, Mexico 2 22 January 14.3 2.5× Compton California, United States 1 21 January 13.3 2.4×
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 43 of 106 episodes in the United States and Mexico 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 Western United States, January 2026 19 Bars: cities reached; colour: the level of the episode's highest daily reading. All 106 .
Use this page SmogRank, Western United States, January 2026: 19 cities with PM2.5 at twice their usual or more, 21 to 23 January 2026, smogrank.com/episodes/2026-01-western-united-states (accessed 2 October 2026).
Copy citation Download top 10 (PNG)
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.
