SmogRank / Mexico / Yucatán / Mérida

Mérida, month by month

Mérida has a measured daily mean on 431 days since 4 April 2024. Its worst month was August 2026, at 78 US AQI (23.7 µg/m³), 182nd of 2,896 cities on that month's world ranking. Its cleanest was December 2025, at 45 US AQI (8.1 µg/m³).

Every month since 2024

2026too few days for a mean (a year needs 199)185 days measured
Jan47#1,358Feb53#1,368Mar20 daysApr20 daysMay15 daysJun18 daysJul19 daysAug78#182Sep18 daysOctnone
2025too few days for a mean (a year needs 256)227 days measured
JannoneFebnoneMar19 daysApr59#643May69#305Jun16 daysJul69#236Aug58#654Sep55#527Oct53#546Nov51#1,229Dec45#1,810
2024too few days for a mean (a year needs 257)19 days measured
JanFebMarApr11 daysMay5 daysJun1 dayJul1 dayAugnoneSepnoneOct1 dayNovnoneDecnone
Each square is a month's mean PM2.5 in US AQI from Mérida'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 Mérida marked; each year, the year's.
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

20 months
MonthWhy
Oct 2026No day measured. The others: 5 with no readings from the monitor, 6 with readings for part of the day (a day needs 18 hours).
Sep 202618 of 30 days measured; a month needs 21. The others: 1 with no readings from the monitor, 11 with readings for part of the day (a day needs 18 hours).
Jul 202619 of 31 days measured; a month needs 22. The others: 12 with under 18 hours of readings or readings that failed our checks.
Jun 202618 of 30 days measured; a month needs 21. The others: 12 with under 18 hours of readings or readings that failed our checks.
May 202615 of 31 days measured; a month needs 22. The others: 16 with under 18 hours of readings or readings that failed our checks.
Apr 202620 of 30 days measured; a month needs 21. The others: 10 with under 18 hours of readings or readings that failed our checks.
Mar 202620 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks.
Jun 202516 of 30 days measured; a month needs 21. The others: 14 with under 18 hours of readings or readings that failed our checks.
Mar 202519 of 31 days measured; a month needs 22. The others: 12 with under 18 hours of readings or readings that failed our checks.
Feb 2025No day measured. The others: 28 with under 18 hours of readings or readings that failed our checks.
Jan 2025No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Dec 2024No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Nov 2024No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Oct 20241 of 31 days measured; a month needs 22. The others: 30 with under 18 hours of readings or readings that failed our checks.
Sep 2024No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Aug 2024No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Jul 20241 of 31 days measured; a month needs 22. The others: 30 with under 18 hours of readings or readings that failed our checks.
Jun 20241 of 30 days measured; a month needs 21. The others: 29 with under 18 hours of readings or readings that failed our checks.
May 20245 of 31 days measured; a month needs 22. The others: 26 with under 18 hours of readings or readings that failed our checks.
Apr 202411 of 30 days measured; a month needs 21. The others: 16 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.

Mérida's worst months

MonthUS AQIDays measuredWorld rank
August 2026 7823.7 µg/m³27 of 31182ndof 2,896
July 2025 6918.8 µg/m³22 of 31236thof 2,889
May 2025 6918.5 µg/m³24 of 31305thof 2,826
April 2025 5913.2 µg/m³22 of 30643rdof 2,951
August 2025 5812.6 µg/m³23 of 31654thof 2,901
September 2025 5511.3 µg/m³24 of 30527thof 3,104

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.

Mérida's worst days

DayUS AQI
13 Jul 2026 412281.0 µg/m³
17 Jul 2026 189109.0 µg/m³
12 Jul 2026 18198.2 µg/m³
16 Aug 2026 15662.1 µg/m³
14 Aug 2026 15459.9 µg/m³
19 Aug 2026 14151.9 µg/m³
18 Jul 2026 13649.6 µg/m³
17 Aug 2026 11440.9 µg/m³
15 Jul 2025 10938.9 µg/m³
14 May 2024 10838.2 µg/m³

Daily means, the highest since 4 Apr 2024; 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, Mérida, Mexico, 4 Apr 2024 – 27 Sep 2026. Monitor data from Sinaica Mexico via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/mx/merida/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.

Mérida 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).