SmogRank / Thailand / Rayong / Rayong

Rayong, month by month

Rayong has a measured daily mean on 776 days since 1 January 2023. Its worst month was January 2024, at 101 US AQI (35.7 µg/m³), 85th of 2,385 cities on that month's world ranking. Its cleanest was June 2024, at 47 US AQI (8.5 µg/m³).

Every month since 2023

202669 so far256 days measured390th of 2,791 in the world
Jan85#201Feb80#390Mar77#503Apr72#399May65#364Jun60#378Jul3 daysAug59#471Sep58#457Oct61#250
2025too few days for a mean (a year needs 256)224 days measured
Jan5 daysFeb92#201Mar82#417Apr56#808May54#720Jun54#1,044JulnoneAug6 daysSep53#690Oct10 daysNov12 daysDec74#455
2024too few days for a mean (a year needs 257)204 days measured
Jan101#85Feb75#180Mar20 daysApr62#399May61#320Jun47#1,125Jul19 daysAug19 daysSep5 daysOct2 daysNov3 daysDec1 day
2023too few days for a mean (a year needs 256)92 days measured
Jan84#84Feb2 daysMar9 daysApr18 daysMay15 daysJun13 daysJul6 daysAug3 daysSep3 daysOctnoneNovnoneDecnone
Each square is a month's mean PM2.5 in US AQI from Rayong'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 Rayong 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

24 months
MonthWhy
Jul 20263 of 31 days measured; a month needs 22. The others: 28 with under 18 hours of readings or readings that failed our checks.
Nov 202512 of 30 days measured; a month needs 21. The others: 18 with under 18 hours of readings or readings that failed our checks.
Oct 202510 of 31 days measured; a month needs 22. The others: 21 with under 18 hours of readings or readings that failed our checks.
Aug 20256 of 31 days measured; a month needs 22. The others: 25 with under 18 hours of readings or readings that failed our checks.
Jul 2025No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Jan 20255 of 31 days measured; a month needs 22. The others: 26 with under 18 hours of readings or readings that failed our checks.
Dec 20241 of 31 days measured; a month needs 22. The others: 30 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 20242 of 31 days measured; a month needs 22. The others: 29 with under 18 hours of readings or readings that failed our checks.
Sep 20245 of 30 days measured; a month needs 21. The others: 25 with under 18 hours of readings or readings that failed our checks.
Aug 202419 of 31 days measured; a month needs 22. The others: 12 with under 18 hours of readings or readings that failed our checks.
Jul 202419 of 31 days measured; a month needs 22. The others: 12 with under 18 hours of readings or readings that failed our checks.
Mar 202420 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks.
Dec 2023No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Nov 2023No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Oct 2023No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Sep 20233 of 30 days measured; a month needs 21. The others: 27 with under 18 hours of readings or readings that failed our checks.
Aug 20233 of 31 days measured; a month needs 22. The others: 28 with under 18 hours of readings or readings that failed our checks.
Jul 20236 of 31 days measured; a month needs 22. The others: 1 missing from OpenAQ's archive, 24 with under 18 hours of readings or readings that failed our checks.
Jun 202313 of 30 days measured; a month needs 21. The others: 17 with under 18 hours of readings or readings that failed our checks.
May 202315 of 31 days measured; a month needs 22. The others: 16 with under 18 hours of readings or readings that failed our checks.
Apr 202318 of 30 days measured; a month needs 21. The others: 2 missing from OpenAQ's archive, 10 with under 18 hours of readings or readings that failed our checks.
Mar 20239 of 31 days measured; a month needs 22. The others: 19 missing from OpenAQ's archive, 3 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.

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

Rayong's worst months

MonthUS AQIDays measuredWorld rankEpisode
January 2024 10135.7 µg/m³24 of 3185thof 2,385–
February 2025 9231.0 µg/m³28 of 28201stof 2,633Thailand, 12 to 13 February 2025
January 2026 8527.6 µg/m³31 of 31201stof 2,617–
January 2023 8426.6 µg/m³23 of 3184thof 1,261Northern Thailand and Laos, January and February 2023
March 2025 8225.6 µg/m³28 of 31417thof 2,862Thailand and Laos, March 2025
February 2026 8024.7 µg/m³28 of 28390thof 2,866–

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.

Rayong's worst days

DayUS AQIEpisode
25 Jan 2025 15662.8 µg/m³Northern Thailand, January 2025
24 Jan 2025 15662.5 µg/m³Northern Thailand, January 2025
1 Feb 2023 15459.5 µg/m³Northern Thailand and Laos, January and February 2023
12 Feb 2025 15359.0 µg/m³Thailand, 12 to 13 February 2025
24 Jan 2023 15257.0 µg/m³–
13 Feb 2025 14754.3 µg/m³Thailand, 12 to 13 February 2025
14 Feb 2024 14653.9 µg/m³Thailand, February 2024
24 Mar 2025 14051.2 µg/m³Thailand and Laos, March 2025
23 Mar 2025 13850.5 µg/m³Thailand and Laos, March 2025
28 Jan 2024 13850.4 µg/m³–

Daily means, the highest since 1 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, Rayong, Thailand, 1 Jan 2023 – 12 Oct 2026. Monitor data from Air4Thai via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/th/rayong/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.

Rayong 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).