SmogRank / Mexico / Querétaro / San Juan del Río

San Juan del Río, month by month

San Juan del Río has a measured daily mean on 865 days since 10 January 2023. Its worst month was May 2025, at 71 US AQI (19.7 µg/m³), 277th of 2,826 cities on that month's world ranking. Its cleanest was September 2023, at 36 US AQI (6.5 µg/m³).

Every month since 2023

202660 so far245 days measured610th of 2,793 in the world
Jan64#675Feb67#646Mar63#777Apr15 daysMay64#384Jun19 daysJul59#654Aug57#531Sep54#578Oct37#1,513
202559 for the year293 days measured511th of 2,681 in the world
Jan7 daysFeb1 dayMar21 daysApr70#382May71#277Jun52#1,481Jul56#919Aug53#1,173Sep45#1,205Oct52#583Nov60#638Dec59#828
2024too few days for a mean (a year needs 257)168 days measured
Jan16 daysFeb12 daysMar11 daysApr4 daysMay20 daysJun63#194Jul52#832Aug48#962Sep9 daysOct10 daysNov3 daysDec4 days
2023too few days for a mean (a year needs 256)159 days measured
Jan11 daysFeb2 daysMar9 daysApr10 daysMay5 daysJun2 daysJul11 daysAug20 daysSep36#1,654Oct14 daysNov52#643Dec52#850
Each square is a month's mean PM2.5 in US AQI from San Juan del Río's measured days, with its place on that month's world ranking under it. A month has a mean once 70% of its days are measured, the rule the monthly rankings use; under that, the square gives the days measured. Each square opens that month's ranking with San Juan del Río marked; each year, the year's. A dashed square is the running month, so far.
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

Months without a mean, and why

23 months
MonthWhy
Jun 202619 of 30 days measured; a month needs 21. The others: 11 with under 18 hours of readings or readings that failed our checks.
Apr 202615 of 30 days measured; a month needs 21. The others: 15 with under 18 hours of readings or readings that failed our checks.
Mar 202521 of 31 days measured; a month needs 22. The others: 10 with under 18 hours of readings or readings that failed our checks.
Feb 20251 of 28 days measured; a month needs 20. The others: 27 with under 18 hours of readings or readings that failed our checks.
Jan 20257 of 31 days measured; a month needs 22. The others: 24 with under 18 hours of readings or readings that failed our checks.
Dec 20244 of 31 days measured; a month needs 22. The others: 27 with under 18 hours of readings or readings that failed our checks.
Nov 20243 of 30 days measured; a month needs 21. The others: 27 with under 18 hours of readings or readings that failed our checks.
Oct 202410 of 31 days measured; a month needs 22. The others: 21 with under 18 hours of readings or readings that failed our checks.
Sep 20249 of 30 days measured; a month needs 21. The others: 21 with under 18 hours of readings or readings that failed our checks.
May 202420 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks.
Apr 20244 of 30 days measured; a month needs 21. The others: 26 with under 18 hours of readings or readings that failed our checks.
Mar 202411 of 31 days measured; a month needs 22. The others: 20 with under 18 hours of readings or readings that failed our checks.
Feb 202412 of 29 days measured; a month needs 21. The others: 17 with under 18 hours of readings or readings that failed our checks.
Jan 202416 of 31 days measured; a month needs 22. The others: 15 with under 18 hours of readings or readings that failed our checks.
Oct 202314 of 31 days measured; a month needs 22. The others: 17 with under 18 hours of readings or readings that failed our checks.
Aug 202320 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks.
Jul 202311 of 31 days measured; a month needs 22. The others: 1 missing from OpenAQ's archive, 19 with under 18 hours of readings or readings that failed our checks.
Jun 20232 of 30 days measured; a month needs 21. The others: 28 with under 18 hours of readings or readings that failed our checks.
May 20235 of 31 days measured; a month needs 22. The others: 26 with under 18 hours of readings or readings that failed our checks.
Apr 202310 of 30 days measured; a month needs 21. The others: 3 missing from OpenAQ's archive, 17 with under 18 hours of readings or readings that failed our checks.
Mar 20239 of 31 days measured; a month needs 22. The others: 20 missing from OpenAQ's archive, 2 with under 18 hours of readings or readings that failed our checks.
Feb 20232 of 28 days measured; a month needs 20. The others: 25 missing from OpenAQ's archive, 1 with under 18 hours of readings or readings that failed our checks.
Jan 202311 of 31 days measured; a month needs 22. The others: 7 missing from OpenAQ's archive, 4 with under 18 hours of readings or readings that failed our checks.

A day counts once 18 hours of it are measured; a month needs 70% of its days.

San Juan del Río's worst months

MonthUS AQIDays measuredWorld rankEpisode
May 2025 7119.7 µg/m³30 of 31277thof 2,826–
April 2025 7019.2 µg/m³22 of 30382ndof 2,951–
February 2026 6717.9 µg/m³28 of 28646thof 2,866–
January 2026 6416.3 µg/m³31 of 31675thof 2,617Mexico, January 2026
Southern Mexico, January 2026
May 2026 6416.0 µg/m³28 of 31384thof 2,874–
March 2026 6315.8 µg/m³31 of 31777thof 2,971–

Monthly means over the days measured; finished months only. World rank: its place on that month's world ranking of every city with enough days. Each month opens that ranking.

San Juan del Río's worst days

DayUS AQIEpisode
20 Mar 2025 13950.8 µg/m³Southern Mexico, March 2025
11 May 2024 12244.2 µg/m³–
7 Jun 2024 11239.8 µg/m³Southern Mexico, June 2024
3 May 2023 11139.7 µg/m³–
6 May 2024 10838.5 µg/m³–
4 Oct 2023 10336.5 µg/m³–
4 May 2023 10135.6 µg/m³–
9 May 2024 10135.6 µg/m³–
10 May 2024 10035.3 µg/m³–
14 May 2024 9934.7 µg/m³–

Daily means, the highest since 10 Jan 2023; the WHO's daily guideline is 15 µg/m³. Each date opens that day's world ranking, and each episode the bad-air spell it was part of.

Use this history

SmogRank, PM2.5 monthly and daily means, San Juan del Río, Mexico, 10 Jan 2023 – 11 Oct 2026. Monitor data from Sinaica Mexico via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/mx/san-juan-del-rio/history (accessed 12 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.

San Juan del Río now: the last 24 hours, its ranks today and the last 12 months day by day.

Updated 2026-10-12 22:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index. Some low-cost readings: Sensor.Community, ODbL (data and licence). Some readings: Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); RMCAB (Secretaría Distrital de Ambiente, Bogotá); Love My Air (City and County of Denver), no reuse terms published (why we use them).