SmogRank / Australia / Queensland / Cairns

Cairns, month by month

Cairns has a measured daily mean on 1,102 days since 31 March 2023. Its worst month was October 2025, at 51 US AQI (9.1 µg/m³), 665th of 2,614 cities on that month's world ranking. Its cleanest was January 2026, at 19 US AQI (3.4 µg/m³). 2025 averaged 31 US AQI (5.6 µg/m³), against 33 US AQI (5.9 µg/m³) in 2024.

Every month since 2023

202623 so far201 days measured2,736th of 2,791 in the world

Jan19#2,554 Feb22#2,737 Mar22#2,809 Apr24#2,656 May25#2,508 Jun26#2,218Jul11 daysAugnoneSepnoneOct26#2,357

202531 for the year363 days measured2,438th of 2,681 in the world

Jan26#2,295 Feb24#2,474 Mar21#2,708 Apr28#2,558 May27#2,362 Jun26#2,342 Jul31#2,452 Aug38#2,217 Sep38#1,767 Oct51#665 Nov36#2,039 Dec27#2,738

202433 for the year348 days measured1,801st of 2,097 in the world

Jan26#2,152 Feb26#2,218Mar21 daysApr28#1,941 May30#2,178 Jun32#2,112 Jul33#2,002 Aug37#1,634 Sep50#595 Oct39#1,080 Nov33#2,017 Dec31#2,194

2023too few days for a mean (a year needs 256)190 days measured

JanFebMar1 dayApr19 daysMay17 daysJun11 daysJul16 daysAug19 daysSep42#1,317Oct20 daysNov39#1,448 Dec39#1,545

Each square is a month's mean PM2.5 in US AQI from Cairns'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 Cairns 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

11 months

Month	Why
Sep 2026	No day measured. The others: 30 with readings for part of the day (a day needs 18 hours).
Aug 2026	No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Jul 2026	11 of 31 days measured; a month needs 22. The others: 20 with under 18 hours of readings or readings that failed our checks.
Mar 2024	21 of 31 days measured; a month needs 22. The others: 10 with under 18 hours of readings or readings that failed our checks.
Oct 2023	20 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks.
Aug 2023	19 of 31 days measured; a month needs 22. The others: 12 with under 18 hours of readings or readings that failed our checks.
Jul 2023	16 of 31 days measured; a month needs 22. The others: 1 missing from OpenAQ's archive, 14 with under 18 hours of readings or readings that failed our checks.
Jun 2023	11 of 30 days measured; a month needs 21. The others: 19 with under 18 hours of readings or readings that failed our checks.
May 2023	17 of 31 days measured; a month needs 22. The others: 14 with under 18 hours of readings or readings that failed our checks.
Apr 2023	19 of 30 days measured; a month needs 21. The others: 2 missing from OpenAQ's archive, 9 with under 18 hours of readings or readings that failed our checks.
Mar 2023	1 of 31 days measured; a month needs 22.

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

Cairns's worst months

Month	US AQI	Days measured	World rank
October 2025	519.1 µg/m³	31 of 31	665thof 2,614
September 2024	509.0 µg/m³	30 of 30	595thof 2,010
September 2023	427.5 µg/m³	30 of 30	1,317thof 2,176
October 2024	397.1 µg/m³	31 of 31	1,080thof 2,020
November 2023	397.0 µg/m³	29 of 30	1,448thof 2,243
December 2023	397.0 µg/m³	28 of 31	1,545thof 2,247

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.

Cairns's worst days

Day	US AQI
4 Oct 2025	8628.1 µg/m³
16 Aug 2024	8627.7 µg/m³
3 Oct 2025	7823.5 µg/m³
25 Sept 2024	7723.2 µg/m³
29 Oct 2023	7522.2 µg/m³
1 Oct 2025	7521.9 µg/m³
5 Oct 2025	7120.1 µg/m³
17 Aug 2024	6818.1 µg/m³
26 Sept 2024	6416.2 µg/m³
1 Sept 2025	6416.0 µg/m³

Daily means, the highest since 31 Mar 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, Cairns, Australia, 31 Mar 2023 – 12 Oct 2026. Monitor data from Queensland Government, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/au/cairns/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.

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

Updated 2026-10-12 20:07 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).