SmogRank / Mexico / Nuevo León / Monterrey

Monterrey, month by month

Monterrey has a measured daily mean on 897 days since 10 January 2023. Its worst month was December 2023, at 78 US AQI (23.6 µg/m³), 107th of 2,247 cities on that month's world ranking. Its cleanest was September 2025, at 55 US AQI (11.5 µg/m³).

Every month since 2023

202663 so far276 days measured532nd of 2,791 in the world
Jan63#707Feb65#701Mar64#769Apr71#410May63#397Jun56#487Jul66#418Aug63#372Sep58#457Oct52#608
202567 for the year308 days measured314th of 2,681 in the world
Jan13 daysFeb6 daysMar18 daysApr74#301May76#220Jun60#573Jul65#309Aug61#416Sep55#506Oct60#375Nov67#475Dec64#680
2024too few days for a mean (a year needs 257)97 days measured
Jan15 daysFeb12 daysMar7 daysApr11 daysMay12 daysJun3 daysJul4 daysAug5 daysSep3 daysOct7 daysNov10 daysDec8 days
2023too few days for a mean (a year needs 256)216 days measured
Jan15 daysFeb2 daysMar11 daysApr72#108May6 daysJun3 daysJul19 daysAug62#191Sep58#271Oct17 daysNov71#77Dec78#107
Each square is a month's mean PM2.5 in US AQI from Monterrey'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 Monterrey 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

22 months
MonthWhy
Mar 202518 of 31 days measured; a month needs 22. The others: 13 with under 18 hours of readings or readings that failed our checks.
Feb 20256 of 28 days measured; a month needs 20. The others: 22 with under 18 hours of readings or readings that failed our checks.
Jan 202513 of 31 days measured; a month needs 22. The others: 18 with under 18 hours of readings or readings that failed our checks.
Dec 20248 of 31 days measured; a month needs 22. The others: 23 with under 18 hours of readings or readings that failed our checks.
Nov 202410 of 30 days measured; a month needs 21. The others: 20 with under 18 hours of readings or readings that failed our checks.
Oct 20247 of 31 days measured; a month needs 22. The others: 24 with under 18 hours of readings or readings that failed our checks.
Sep 20243 of 30 days measured; a month needs 21. The others: 27 with under 18 hours of readings or readings that failed our checks.
Aug 20245 of 31 days measured; a month needs 22. The others: 26 with under 18 hours of readings or readings that failed our checks.
Jul 20244 of 31 days measured; a month needs 22. The others: 27 with under 18 hours of readings or readings that failed our checks.
Jun 20243 of 30 days measured; a month needs 21. The others: 27 with under 18 hours of readings or readings that failed our checks.
May 202412 of 31 days measured; a month needs 22. The others: 19 with under 18 hours of readings or readings that failed our checks.
Apr 202411 of 30 days measured; a month needs 21. The others: 19 with under 18 hours of readings or readings that failed our checks.
Mar 20247 of 31 days measured; a month needs 22. The others: 24 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 202415 of 31 days measured; a month needs 22. The others: 16 with under 18 hours of readings or readings that failed our checks.
Oct 202317 of 31 days measured; a month needs 22. The others: 14 with under 18 hours of readings or readings that failed our checks.
Jul 202319 of 31 days measured; a month needs 22. The others: 1 missing from OpenAQ's archive, 11 with under 18 hours of readings or readings that failed our checks.
Jun 20233 of 30 days measured; a month needs 21. The others: 27 with under 18 hours of readings or readings that failed our checks.
May 20236 of 31 days measured; a month needs 22. The others: 25 with under 18 hours of readings or readings that failed our checks.
Mar 202311 of 31 days measured; a month needs 22. The others: 20 missing from OpenAQ's archive.
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 202315 of 31 days measured; a month needs 22. The others: 6 missing from OpenAQ's archive, 1 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.

Monterrey's worst months

MonthUS AQIDays measuredWorld rankEpisode
December 2023 7823.6 µg/m³31 of 31107thof 2,247–
May 2025 7622.6 µg/m³31 of 31220thof 2,826Southern United States and Mexico, May 2025
April 2025 7421.3 µg/m³30 of 30301stof 2,951Southern United States and Mexico, March and April 2025
April 2023 7220.3 µg/m³27 of 30108thof 1,622–
April 2026 7119.8 µg/m³26 of 30410thof 2,941–
November 2023 7119.6 µg/m³30 of 3077thof 2,243–

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.

Monterrey's worst days

DayUS AQIEpisode
28 Jan 2023 17082.5 µg/m³Northern Mexico and United States, January 2023
19 Mar 2025 15865.5 µg/m³–
5 Dec 2024 15156.2 µg/m³–
1 Jan 2024 13147.7 µg/m³–
29 Jan 2023 13147.5 µg/m³Northern Mexico and United States, January 2023
15 Feb 2025 13047.3 µg/m³–
10 Jan 2024 12947.0 µg/m³–
10 May 2024 12947.0 µg/m³Southern United States and Mexico, 7 to 10 May 2024
23 May 2024 12745.9 µg/m³Southern United States and Mexico, 19 to 28 May 2024
12 Jan 2024 12645.5 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, Monterrey, Mexico, 10 Jan 2023 – 10 Oct 2026. Monitor data from Sinaica Mexico via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/mx/monterrey/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.

Monterrey now: the last 24 hours, its ranks today and the last 12 months day by day.

Updated 2026-10-12 17:07 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).