SmogRank / Episodes / Mexico

Southern Mexico, January 2023

For 3 days, from 18 to 20 January 2023, 10 cities in Mexico had PM2.5 at least twice their usual for the time of year. The worst reading was Guadalajara, Jalisco, Mexico: 61.4 µg/m³ on 19 January, about 2.2× its usual 28.0.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached10in 1 country
Days318 to 20 January 2023
Worst day19 January7 cities counted
Furthest above usual3.0×Celaya

Day by day

19 January 7 cities at twice their usual or more
AbasoloIrapuatoGuanajuatoTolucaSan Luis de la PazXonacatlánSan Salvador TizatlalliSan Mateo AtencoLeón de los AldamaNaucalpan de JuárezMexico CityEcatepec de MorelosCiudad NezahualcoyotlCuernavacaPachuca de SotoZacatepec de HidalgoCuautlaSan Luis PotosíCalpulalpanAguascalientesTlaquepaqueCholulaHacienda Santa FeApizacoZapopanTúxpam de Rodríguez CanoSan Francisco TlalcilalcalpanTlaxcalaGuadalajaraPueblaSan Miguel de AllendeSan Juan del RíoSantiago de QuerétaroSalamancaTepeji del Río de OcampoCelaya
15 Jan1617181920212223
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

GuadalajaraGuadalajara, 15 January: no readingGuadalajara, 16 January: 31.6 µg/m³, 1.1× usualGuadalajara, 17 January: 66.5 µg/m³, 2.4× usualGuadalajara, 18 January: 38.6 µg/m³, 1.4× usualGuadalajara, 19 January: 61.4 µg/m³, 2.2× usualGuadalajara, 20 January: 43.0 µg/m³, 1.5× usualGuadalajara, 21 January: no readingGuadalajara, 22 January: no readingGuadalajara, 23 January: 21.3 µg/m³, 0.8× usualSan Francisco Tlalc…San Francisco Tlalcilalcalpan, 15 January: no readingSan Francisco Tlalcilalcalpan, 16 January: 51.0 µg/m³, 1.9× usualSan Francisco Tlalcilalcalpan, 17 January: 54.5 µg/m³, 2.0× usualSan Francisco Tlalcilalcalpan, 18 January: 53.0 µg/m³, 2.0× usualSan Francisco Tlalcilalcalpan, 19 January: 52.6 µg/m³, 2.0× usualSan Francisco Tlalcilalcalpan, 20 January: 56.2 µg/m³, 2.1× usualSan Francisco Tlalcilalcalpan, 21 January: 55.7 µg/m³, 2.1× usualSan Francisco Tlalcilalcalpan, 22 January: no readingSan Francisco Tlalcilalcalpan, 23 January: 46.3 µg/m³, 1.7× usualPueblaPuebla, 15 January: no readingPuebla, 16 January: 32.8 µg/m³, 1.7× usualPuebla, 17 January: 48.0 µg/m³, 2.5× usualPuebla, 18 January: 38.5 µg/m³, 2.0× usualPuebla, 19 January: 41.6 µg/m³, 2.2× usualPuebla, 20 January: 37.4 µg/m³, 2.0× usualPuebla, 21 January: 15.8 µg/m³, 0.8× usualPuebla, 22 January: no readingPuebla, 23 January: 35.0 µg/m³, 1.8× usualTlaxcalaTlaxcala, 15 January: no readingTlaxcala, 16 January: no readingTlaxcala, 17 January: 35.1 µg/m³, 2.1× usualTlaxcala, 18 January: 35.6 µg/m³, 2.1× usualTlaxcala, 19 January: no readingTlaxcala, 20 January: no readingTlaxcala, 21 January: no readingTlaxcala, 22 January: no readingTlaxcala, 23 January: no readingCelayaCelaya, 15 January: no readingCelaya, 16 January: 25.3 µg/m³, 1.3× usualCelaya, 17 January: 29.4 µg/m³, 1.5× usualCelaya, 18 January: 48.7 µg/m³, 2.6× usualCelaya, 19 January: 39.2 µg/m³, 2.1× usualCelaya, 20 January: 56.4 µg/m³, 3.0× usualCelaya, 21 January: 58.6 µg/m³, 3.1× usualCelaya, 22 January: no readingCelaya, 23 January: 34.1 µg/m³, 1.8× usualSantiago de Queréta…Santiago de Querétaro, 15 January: no readingSantiago de Querétaro, 16 January: no readingSantiago de Querétaro, 17 January: no readingSantiago de Querétaro, 18 January: 36.2 µg/m³, 2.2× usualSantiago de Querétaro, 19 January: 43.7 µg/m³, 2.6× usualSantiago de Querétaro, 20 January: 35.1 µg/m³, 2.1× usualSantiago de Querétaro, 21 January: 32.2 µg/m³, 1.9× usualSantiago de Querétaro, 22 January: no readingSantiago de Querétaro, 23 January: 22.9 µg/m³, 1.4× usualSalamancaSalamanca, 15 January: no readingSalamanca, 16 January: no readingSalamanca, 17 January: no readingSalamanca, 18 January: no readingSalamanca, 19 January: 42.6 µg/m³, 2.7× usualSalamanca, 20 January: 35.2 µg/m³, 2.2× usualSalamanca, 21 January: 35.7 µg/m³, 2.2× usualSalamanca, 22 January: no readingSalamanca, 23 January: 25.5 µg/m³, 1.6× usualSan Juan del RíoSan Juan del Río, 15 January: no readingSan Juan del Río, 16 January: no readingSan Juan del Río, 17 January: no readingSan Juan del Río, 18 January: 21.1 µg/m³, 1.5× usualSan Juan del Río, 19 January: 33.7 µg/m³, 2.4× usualSan Juan del Río, 20 January: 33.7 µg/m³, 2.4× usualSan Juan del Río, 21 January: no readingSan Juan del Río, 22 January: no readingSan Juan del Río, 23 January: no readingTepeji del Río de O…Tepeji del Río de Ocampo, 15 January: no readingTepeji del Río de Ocampo, 16 January: 18.7 µg/m³, 1.6× usualTepeji del Río de Ocampo, 17 January: no readingTepeji del Río de Ocampo, 18 January: no readingTepeji del Río de Ocampo, 19 January: 31.2 µg/m³, 2.6× usualTepeji del Río de Ocampo, 20 January: 32.5 µg/m³, 2.7× usualTepeji del Río de Ocampo, 21 January: 19.9 µg/m³, 1.7× usualTepeji del Río de Ocampo, 22 January: no readingTepeji del Río de Ocampo, 23 January: 24.4 µg/m³, 2.0× usualSan Miguel de Allen…San Miguel de Allende, 15 January: no readingSan Miguel de Allende, 16 January: 12.8 µg/m³, 1.1× usualSan Miguel de Allende, 17 January: 18.6 µg/m³, 1.6× usualSan Miguel de Allende, 18 January: 20.0 µg/m³, 1.7× usualSan Miguel de Allende, 19 January: 20.7 µg/m³, 1.8× usualSan Miguel de Allende, 20 January: 26.5 µg/m³, 2.3× usualSan Miguel de Allende, 21 January: 20.2 µg/m³, 1.8× usualSan Miguel de Allende, 22 January: no readingSan Miguel de Allende, 23 January: 16.7 µg/m³, 1.5× usual15 Jan1617181920212223
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.
Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

Every city it reached

CityDaysHighestUsualAbove usual
CelayaGuanajuato, Mexico3 58.621 January19.03.1×
Tepeji del Río de OcampoHidalgo, Mexico2 32.520 January12.02.7×
SalamancaGuanajuato, Mexico2 42.619 January15.92.7×
Santiago de QuerétaroQuerétaro, Mexico3 43.719 January16.62.6×
PueblaPuebla, Mexico2 48.017 January19.02.5×
San Juan del RíoQuerétaro, Mexico2 33.719 January14.12.4×
GuadalajaraJalisco, Mexico1 66.517 January28.02.4×
San Miguel de AllendeGuanajuato, Mexico1 26.520 January11.52.3×
TlaxcalaTlaxcala, Mexico1 35.618 January16.92.1×
San Francisco TlalcilalcalpanMéxico, Mexico1 56.220 January26.92.1×

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 Mexico

Number 4 of 6 episodes in Mexico since our records began, by cities reached.

Bars: cities reached; colour: the level of the episode's highest daily reading.

Use this page

SmogRank, Southern Mexico, January 2023: 10 cities with PM2.5 at twice their usual or more, 18 to 20 January 2023, smogrank.com/episodes/2023-01-southern-mexico (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.