SmogRank / Episodes / Mexico
Northern Mexico and United States, May 2025
For 6 days, from 15 to 20 May 2025, 12 cities in Mexico and the United States had PM2.5 at least twice their usual for the time of year. The worst reading was Ciudad Benito Juárez, Nuevo León, Mexico: 48.9 µg/m³ on 16 May, about 2.5× its usual 19.6.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 12 in 2 countries
Days 6 15 to 20 May 2025
Worst day 17 May 9 cities counted
Furthest above usual 3.8× García
Day by day
Play 17 May 9 cities at twice their usual or more
Live Oak Brownsville Jardines de la Silla San Marcos Saltillo Mission Bend Missouri City Houston Pasadena La Porte Galveston Baytown Mission Corpus Christi Monterrey Santa Catarina Ciudad General Escobedo Ciudad Benito Juárez Cadereyta Jiménez Edinburg San Antonio Laredo Eagle Pass García 12 May 13 14 15 16 17 18 19 20 21 22 23 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
Cadereyta Jiménez Cadereyta Jiménez, 12 May: 21.9 µg/m³, 1.5× usual Cadereyta Jiménez, 13 May: 27.6 µg/m³, 1.9× usual Cadereyta Jiménez, 14 May: 30.7 µg/m³, 2.1× usual Cadereyta Jiménez, 15 May: 33.6 µg/m³, 2.3× usual Cadereyta Jiménez, 16 May: 36.2 µg/m³, 2.5× usual Cadereyta Jiménez, 17 May: 26.0 µg/m³, 1.8× usual Cadereyta Jiménez, 18 May: 30.6 µg/m³, 2.1× usual Cadereyta Jiménez, 19 May: 27.1 µg/m³, 1.9× usual Cadereyta Jiménez, 20 May: 23.1 µg/m³, 1.6× usual Cadereyta Jiménez, 21 May: 30.3 µg/m³, 2.1× usual Cadereyta Jiménez, 22 May: 12.9 µg/m³, 0.9× usual Cadereyta Jiménez, 23 May: 19.1 µg/m³, 1.3× usual García García, 12 May: 16.4 µg/m³, 1.3× usual García, 13 May: 21.9 µg/m³, 1.7× usual García, 14 May: 29.2 µg/m³, 2.3× usual García, 15 May: 33.1 µg/m³, 2.6× usual García, 16 May: no reading García, 17 May: 48.6 µg/m³, 3.8× usual García, 18 May: no reading García, 19 May: 35.2 µg/m³, 2.7× usual García, 20 May: no reading García, 21 May: no reading García, 22 May: no reading García, 23 May: no reading Ciudad General Esco… Ciudad General Escobedo, 12 May: 16.6 µg/m³, 1.2× usual Ciudad General Escobedo, 13 May: 20.9 µg/m³, 1.5× usual Ciudad General Escobedo, 14 May: 26.1 µg/m³, 1.8× usual Ciudad General Escobedo, 15 May: 30.9 µg/m³, 2.1× usual Ciudad General Escobedo, 16 May: 32.3 µg/m³, 2.2× usual Ciudad General Escobedo, 17 May: 33.1 µg/m³, 2.3× usual Ciudad General Escobedo, 18 May: 33.0 µg/m³, 2.3× usual Ciudad General Escobedo, 19 May: 26.9 µg/m³, 1.9× usual Ciudad General Escobedo, 20 May: 26.9 µg/m³, 1.9× usual Ciudad General Escobedo, 21 May: 25.5 µg/m³, 1.8× usual Ciudad General Escobedo, 22 May: 12.1 µg/m³, 0.8× usual Ciudad General Escobedo, 23 May: 19.0 µg/m³, 1.3× usual Laredo Laredo, 12 May: 6.7 µg/m³, 0.5× usual Laredo, 13 May: 9.5 µg/m³, 0.8× usual Laredo, 14 May: 17.0 µg/m³, 1.4× usual Laredo, 15 May: 28.0 µg/m³, 2.2× usual Laredo, 16 May: 29.5 µg/m³, 2.4× usual Laredo, 17 May: 32.9 µg/m³, 2.6× usual Laredo, 18 May: 26.3 µg/m³, 2.1× usual Laredo, 19 May: 29.1 µg/m³, 2.3× usual Laredo, 20 May: 30.8 µg/m³, 2.5× usual Laredo, 21 May: 26.5 µg/m³, 2.1× usual Laredo, 22 May: 16.6 µg/m³, 1.3× usual Laredo, 23 May: 15.0 µg/m³, 1.2× usual Ciudad Benito Juárez Ciudad Benito Juárez, 12 May: 24.3 µg/m³, 1.2× usual Ciudad Benito Juárez, 13 May: 23.7 µg/m³, 1.2× usual Ciudad Benito Juárez, 14 May: 30.3 µg/m³, 1.5× usual Ciudad Benito Juárez, 15 May: 39.7 µg/m³, 2.0× usual Ciudad Benito Juárez, 16 May: 48.9 µg/m³, 2.5× usual Ciudad Benito Juárez, 17 May: 42.2 µg/m³, 2.2× usual Ciudad Benito Juárez, 18 May: 38.6 µg/m³, 2.0× usual Ciudad Benito Juárez, 19 May: 34.8 µg/m³, 1.8× usual Ciudad Benito Juárez, 20 May: 32.7 µg/m³, 1.7× usual Ciudad Benito Juárez, 21 May: 30.0 µg/m³, 1.5× usual Ciudad Benito Juárez, 22 May: no reading Ciudad Benito Juárez, 23 May: 24.9 µg/m³, 1.3× usual Monterrey Monterrey, 12 May: 15.3 µg/m³, 0.8× usual Monterrey, 13 May: 21.5 µg/m³, 1.1× usual Monterrey, 14 May: 30.6 µg/m³, 1.6× usual Monterrey, 15 May: 34.2 µg/m³, 1.7× usual Monterrey, 16 May: 39.2 µg/m³, 2.0× usual Monterrey, 17 May: 37.3 µg/m³, 1.9× usual Monterrey, 18 May: 37.1 µg/m³, 1.9× usual Monterrey, 19 May: 29.1 µg/m³, 1.5× usual Monterrey, 20 May: 30.8 µg/m³, 1.6× usual Monterrey, 21 May: 30.8 µg/m³, 1.6× usual Monterrey, 22 May: 18.3 µg/m³, 0.9× usual Monterrey, 23 May: 22.7 µg/m³, 1.2× usual San Antonio San Antonio, 12 May: 6.7 µg/m³, 0.6× usual San Antonio, 13 May: 9.5 µg/m³, 0.9× usual San Antonio, 14 May: 15.3 µg/m³, 1.4× usual San Antonio, 15 May: 21.4 µg/m³, 2.0× usual San Antonio, 16 May: 25.9 µg/m³, 2.4× usual San Antonio, 17 May: 27.9 µg/m³, 2.6× usual San Antonio, 18 May: 14.6 µg/m³, 1.4× usual San Antonio, 19 May: 23.2 µg/m³, 2.2× usual San Antonio, 20 May: 15.8 µg/m³, 1.5× usual San Antonio, 21 May: 11.3 µg/m³, 1.1× usual San Antonio, 22 May: 14.9 µg/m³, 1.4× usual San Antonio, 23 May: 10.3 µg/m³, 1.0× usual Santa Catarina Santa Catarina, 12 May: 17.1 µg/m³, 1.0× usual Santa Catarina, 13 May: no reading Santa Catarina, 14 May: no reading Santa Catarina, 15 May: 33.2 µg/m³, 2.0× usual Santa Catarina, 16 May: 34.2 µg/m³, 2.0× usual Santa Catarina, 17 May: 37.2 µg/m³, 2.2× usual Santa Catarina, 18 May: 34.3 µg/m³, 2.0× usual Santa Catarina, 19 May: 33.3 µg/m³, 2.0× usual Santa Catarina, 20 May: 23.3 µg/m³, 1.4× usual Santa Catarina, 21 May: 28.7 µg/m³, 1.7× usual Santa Catarina, 22 May: no reading Santa Catarina, 23 May: 17.6 µg/m³, 1.0× usual Edinburg Edinburg, 12 May: 11.0 µg/m³, 0.8× usual Edinburg, 13 May: 8.4 µg/m³, 0.6× usual Edinburg, 14 May: 17.6 µg/m³, 1.4× usual Edinburg, 15 May: 16.8 µg/m³, 1.3× usual Edinburg, 16 May: 26.8 µg/m³, 2.1× usual Edinburg, 17 May: 29.7 µg/m³, 2.3× usual Edinburg, 18 May: 18.9 µg/m³, 1.5× usual Edinburg, 19 May: 29.4 µg/m³, 2.3× usual Edinburg, 20 May: 33.4 µg/m³, 2.6× usual Edinburg, 21 May: 19.4 µg/m³, 1.5× usual Edinburg, 22 May: 14.3 µg/m³, 1.1× usual Edinburg, 23 May: 11.6 µg/m³, 0.9× usual Eagle Pass Eagle Pass, 12 May: 4.9 µg/m³, 0.5× usual Eagle Pass, 13 May: 9.1 µg/m³, 0.9× usual Eagle Pass, 14 May: 13.3 µg/m³, 1.3× usual Eagle Pass, 15 May: 23.2 µg/m³, 2.2× usual Eagle Pass, 16 May: 24.5 µg/m³, 2.3× usual Eagle Pass, 17 May: 29.1 µg/m³, 2.8× usual Eagle Pass, 18 May: 29.8 µg/m³, 2.8× usual Eagle Pass, 19 May: 23.0 µg/m³, 2.2× usual Eagle Pass, 20 May: 11.1 µg/m³, 1.1× usual Eagle Pass, 21 May: 14.5 µg/m³, 1.4× usual Eagle Pass, 22 May: 17.3 µg/m³, 1.6× usual Eagle Pass, 23 May: 12.8 µg/m³, 1.2× usual Mission Mission, 12 May: 6.2 µg/m³, 0.4× usual Mission, 13 May: 8.1 µg/m³, 0.6× usual Mission, 14 May: 15.0 µg/m³, 1.0× usual Mission, 15 May: 16.9 µg/m³, 1.1× usual Mission, 16 May: 25.4 µg/m³, 1.7× usual Mission, 17 May: 25.7 µg/m³, 1.7× usual Mission, 18 May: 17.9 µg/m³, 1.2× usual Mission, 19 May: 26.5 µg/m³, 1.8× usual Mission, 20 May: 29.4 µg/m³, 2.0× usual Mission, 21 May: 19.7 µg/m³, 1.3× usual Mission, 22 May: 13.5 µg/m³, 0.9× usual Mission, 23 May: 12.3 µg/m³, 0.8× usual Corpus Christi Corpus Christi, 12 May: 8.0 µg/m³, 0.6× usual Corpus Christi, 13 May: 10.0 µg/m³, 0.8× usual Corpus Christi, 14 May: 15.4 µg/m³, 1.2× usual Corpus Christi, 15 May: 17.5 µg/m³, 1.4× usual Corpus Christi, 16 May: 20.5 µg/m³, 1.7× usual Corpus Christi, 17 May: 22.2 µg/m³, 1.8× usual Corpus Christi, 18 May: 15.5 µg/m³, 1.3× usual Corpus Christi, 19 May: 21.5 µg/m³, 1.7× usual Corpus Christi, 20 May: 25.4 µg/m³, 2.0× usual Corpus Christi, 21 May: 17.2 µg/m³, 1.4× usual Corpus Christi, 22 May: 10.4 µg/m³, 0.8× usual Corpus Christi, 23 May: 10.3 µg/m³, 0.8× usual 12 May 14 16 18 20 22 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
García Nuevo León, Mexico 3 17 May 12.9 3.8× Eagle Pass Texas, United States 2 18 May 10.5 2.8× Laredo Texas, United States 6 17 May 12.5 2.6× San Antonio Texas, United States 2 17 May 10.7 2.6× Edinburg Texas, United States 3 20 May 13.0 2.6× Cadereyta Jiménez Nuevo León, Mexico 4 16 May 14.3 2.5× Ciudad Benito Juárez Nuevo León, Mexico 4 16 May 19.6 2.5× Ciudad General Escobedo Nuevo León, Mexico 4 17 May 14.4 2.3× Santa Catarina Nuevo León, Mexico 3 17 May 16.8 2.2× Corpus Christi Texas, United States 1 20 May 12.4 2.0× Monterrey Nuevo León, Mexico 3 16 May 19.6 2.0× Mission Texas, United States 1 20 May 14.7 2.0×
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 Mexico and the United States
Number 65 of 106 episodes in Mexico and the United States 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 Northern Mexico and United States, May 2025 12 Bars: cities reached; colour: the level of the episode's highest daily reading. All 106 .
Use this page SmogRank, Northern Mexico and United States, May 2025: 12 cities with PM2.5 at twice their usual or more, 15 to 20 May 2025, smogrank.com/episodes/2025-05-northern-mexico-and-united-states (accessed 2 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.
