AGA GeoAnalitik Study
BL-2026-007

July–September 2026 ran at +1.69 on CPC’s Relative ONI, second since 1950 to 1997’s +1.84.

The weather behind the 2026 burning: El Niño from NOAA’s indices, and the rain at 12 fire points in Sumatra, Kalimantan and Papua from ERA5. The study sets the weather beside the detections; it does not test how much of the burning the weather explains.

NOAA CPC ONI and RONI, 1950–2026; ERA5 rain at the fire points, 2015 to 10 Oct 2026, on local days. Correct as of the study date, 16 Oct 2026; never refreshed.

July–September 2026 stood at +1.69 on RONI and +2.16 on the older ONI, above 2015 on both

RONI first: it is CPC’s official index. On the older ONI, 2026 ranks first. The Indian Ocean Dipole is left out because its licence terms conflict on commercial reuse. NOAA does not endorse this study.

-1.5-1.0-0.50+0.5+1.0+1.5+2.0+2.5
19972015202620232019
DJFMAMJJASON

Figure 1. RONI, three-month means plotted at their middle month, December–February to September–November: 2026 in lime, to July–September, the latest season; 1997, 2015, 2019 and 2023 in grey. ONI and RONI: NOAA Climate Prediction Center (public domain).

RankRONIONI
11997+1.842026+2.16
22026+1.691997+1.79
32015+1.542015+1.73
41965+1.491987+1.46
51972+1.401965+1.27

Table 1. The five highest July–September values since 1950 on each index. On RONI 2026 is second of 77 seasons; on ONI, first.

June–September 2026 was the driest of the 12 seasons since 2015 at 10 of the 12 fire points, and August–September the driest at all 12

The two that missed are Riau’s: Pekanbaru’s June–September was the 10th driest of the 12, after its wettest June, and Dumai’s the 3rd. 1997 compares on El Niño alone: ERA5 rain here starts in 2015.

20262015–2025

Sumatra

Jambi Jambi

2026: 192 mm, driest of 12

Dumai Riau

2026: 662 mm, 3rd driest of 12

Pekanbaru Riau

2026: 702 mm, 10th driest of 12

Ogan Komering Ilir South Sumatra

2026: 172 mm, driest of 12

Palembang South Sumatra

2026: 137 mm, driest of 12

Kalimantan

Ketapang West Kalimantan

2026: 76 mm, driest of 12

Pontianak West Kalimantan

2026: 283 mm, driest of 12

Palangka Raya Central Kalimantan

2026: 133 mm, driest of 12

Pulang Pisau Central Kalimantan

2026: 142 mm, driest of 12

Banjarmasin South Kalimantan

2026: 77 mm, driest of 12

Samarinda East Kalimantan

2026: 287 mm, driest of 12

Papua

Merauke Papua

2026: 32 mm, driest of 12

20152026

Figure 2. June–September rain at each fire point, 2015–2026, one scale per point: 2026 in lime. Points grouped Sumatra, Kalimantan, Papua; each names its province. ERA5 point rain to 10 Oct; days on local clocks (WIB, WITA, WIT). “Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.” The study’s calculation on ERA5, not an ECMWF product.

Dry spells set records at Merauke (92 days), Banjarmasin (73), Ketapang (69), Pulang Pisau (49), Samarinda (45) and Palangka Raya (39); South Sumatra and Jambi set none

A dry spell here is the longest run of days under 1 mm, against the longest in the same window of 2015–2025. Merauke’s run is thin: counted as wet, its four 0.70–0.99 mm days split it 46/42. Dumai (20 days against 13) and Pontianak (18 against 16) set records too, early in the year; Pontianak’s record fails at 0.9 mm. Window 1 Jan – 10 Oct.

Fire pointDays, 2026WhenBest, same windowBest, any whole year
Merauke Papua9211 Jul – 10 Oct33 (2019)43 (2015)
Banjarmasin South Kalimantan7330 Jul – 10 Oct38 (2015)38 (2015)
Ketapang West Kalimantan6930 Jun – 6 Sep22 (2018)22 (2018)
Pulang Pisau Central Kalimantan4930 Jul – 16 Sep37 (2015)37 (2015)
Samarinda East Kalimantan452 Aug – 15 Sep15 (2019)15 (2019)
Palangka Raya Central Kalimantan3931 Jul – 7 Sep31 (2015)31 (2015)
Dumai Riau2019 Jan – 7 Feb13 (2015)13 (2015)
Pontianak West Kalimantan1814 Jan – 31 Jan16 (2019)16 (2019)
Ogan Komering Ilir South Sumatra2229 Aug – 19 Sep59 (2015)78 (2015)
Palembang South Sumatra1931 Aug – 18 Sep38 (2015)38 (2015)
Jambi Jambi1317 Aug – 29 Aug33 (2019)33 (2019)
Pekanbaru Riau106 Aug – 15 Aug14 (2024)14 (2024)

Table 2. Longest run of days under 1 mm of ERA5 rain at each fire point, 1 Jan – 10 Oct 2026 (bar, lime where it is a record), against the longest in the same window of 2015–2025 (grey tick) and in any whole year, the year in brackets. Records first.

Past Malaysian peaks, for scale: 839 at Kuching in 1997 and 746 at Muar in 2013

Readings as reported at the time, not DOE’s validated record. 2005’s date is in conflict between sources. Miri’s 442 (press) against DOE’s 415. This season’s highest in DOE’s archive is on Where it landed.

WhenAPIWhereWhat the source saysReported by
23 Sep 1997839Kuching, SarawakKuching’s 1997 peak, quoted then and since; another report gives 838 the same dayLim Kit Siang
23 Sep 1997838Kuching, Sarawakthe same day in another report, one point lowerThe Korea Times
23 Jun 2013746Muar, JohorMuar’s 2013 peak on DOE’s website, reported that dayThe Star
23 Jun 2013over 750Muar, Johora 2026 retrospective of the same morning says it exceeded 750The Star
11 Aug 2005531Kuala Selangor, Selangorbefore the 2005 emergency declaration, citing DOE; the date is inferredMalaysiakini
1 Aug 2005531Kuala Selangor and Port Klang, Selangorthe 2005 emergency as NADMA listed it, dated 1 Aug, against 11 Aug in the wire copyThe Borneo Post
4 Oct 2015308Shah Alam, Selangorthe highest of 2015 in the reports foundMalay Mail
20 Sep 2019420Sri Aman, SarawakSri Aman’s 2019 peak on the APIMS portalBernama
22 Aug 2019442ILP Miri stationMiri’s 2019 high as the press reported itThe Borneo Post
26 Aug 2019415ILP Miri stationthe same station’s 2019 high as DOE stated itMESTECC and Department of Environment

Table 3. Past peak API readings in Malaysia, each from one report; each outlet’s name links to its report.

Limits
  • The study sets El Niño and rain beside the detections; it does not test how much of the burning they explain.
  • ERA5 rain is a reanalysis at a point, not a rain-gauge reading.
  • 1997 compares on El Niño alone: the study’s ERA5 rain starts in 2015.
  • Seasons are not ranked on haze; past peaks are quoted as reported, for scale.
  • The Indian Ocean Dipole is left out: its licence terms conflict on commercial reuse.
  • The study names no company or concession.

Data, method and credits
  • El Niño: ONI and RONI: NOAA Climate Prediction Center (public domain).
  • Rain: “Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.” ERA5, Copernicus Climate Change Service (C3S) Climate Data Store (CDS), CC BY 4.0.
  • Past peaks: press and official statements, one row each in the study’s research file, with links.
  • No credited source or agency endorses this study, and no figure here is official.
  • Every licence, DOI and the method: Method and credits.