Rainfall dropped by half across Indonesia during a dry season that burned 1.9 million hectares of peatland and rainforest between August and October 2026.
World Weather Attribution (WWA) researchers reported that the severe haze subjected 12.5 million individuals throughout Southeast Asia to dangerous air pollution, triggering upwards of 400,000 respiratory sicknesses solely inside Indonesia.
While a strong El Niño drove the extreme lack of rainfall, human-induced climate change made the season 1.6°C hotter and tripled the likelihood of weeklong hot, dry atmospheric extremes, researchers found.
“The top line of the study is that this year’s El Niño set the conditions for very low rainfall, a major fire season drought, and that this drought was then exacerbated by record heat throughout the fire season, which was made possible due to human-caused climate change,” Theodore Keeping, extreme weather and wildfire researcher at Imperial College London, U.K., shared during an online press briefing covered by Conservation news.
Rainfall Falls Below Normal Levels Across Indonesia
September 2026 ranked as Indonesia’s fifth-driest September since 1991, with rainfall falling below normal levels across 84 percent of the country, Pramudhian Firdaus, a wildfire researcher at Melbourne University, told The Jakarta Post.
Data released by the independent geo-monitoring platform Nusantara Atlas showed that almost 2.88 million hectares of Indonesian territory was affected by fire from January to October 2026, increasing by nearly 1 million hectares in October alone.
Friederike Otto, a professor of climate science at Imperial College London, said climate change impacts increasingly outweigh natural variability.
“Especially on the temperature effects of El Niño, we have already seen in past years … that the effect of climate change is surpassing the effect of El Niño in many cases,” Otto told Conservation news.
Peat Swamp Forest Cover Declines and Government Deploys Aerial Units
Data from the WWA analysis indicates that agricultural drainage and logging caused peat swamp forest reduction to reach 45% in Borneo and 63% in Sumatra between 1990 and 2010.
“Indonesian landscapes have changed dramatically over the last 30 years, with extensive peatland drainage and deforestation creating a landscape that is extremely vulnerable to ignition,” Firdaus said.
As of November 11, 2026, the Indonesian government deployed 35 aerial units across eight provinces to support firefighting efforts, including 15 aircraft for patrols and weather modification operations and 20 helicopters for water bombing, Kompas reported.
The National Disaster Mitigation Agency (BNPB) recorded 521 hotspots of forest and land fires across various regions by Thursday, with affected land reaching 1,332 hectares in BNPB data, Kompas reported.
Meanwhile, smoke from the fires crossed national borders into Malaysia and Singapore, prompting offers of international assistance and renewing regional discussions under the ASEAN Agreement on Transboundary Haze Pollution, The Southeast Asia Desk reported.
“The conditions that we saw this year would simply just not have happened in a world without the human contribution to climate change, even with the very strong El Niño that we’re seeing,” Keeping told The Jakarta Post.
