NASA satellite data show a dramatic uptick in fire hotspots across Indonesia, with smoke from Sumatra detected in Malaysia in late July.
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Army officers and and firefighters try to extinguish fires in peatland areas, Borneo. Image by Aulia Erlangga/CIFOR via Flickr (CC BY-NC-ND 2.0).
Indonesia’s 2025 fire season is spiraling into one of the worst in recent memory, with a sharp spike in hotspots and toxic haze already choking parts of Malaysia.
Forest and peat fires, mostly caused by deliberate land clearing for agriculture, are an annual problem in Indonesia that strain relations with neighboring countries.
July 2025 has seen a dramatic escalation in fire activity across Indonesia with official data from NASA satellites showing a surge in fire hotspots compared with previous months.
NASA’s VIIRS (S-NPP) satellite detected 794 hotspots in July — up nearly tenfold from June and more than thirtyfold from May.
The hotspots in July also represent a more than tenfold increase from the same period last year (68 in July 2024) and are significantly higher than the 532 hotspots recorded in July 2023.
Graph showing hotspots in Indonesia from 2023 to 2025 based on NASA’s VIIRS (S-NPP) satellite. Image courtesy of Indonesia’s Ministry of Environment.
Data from NASA’s Terra and Aqua MODIS satellites paint a similar picture, showing 879 hotspots in July, a more than tenfold increase from May, and are higher than the same period last year (463 in July 2024 and 776 in July 2023).
While VIIRS has finer resolution and detects smaller fires, MODIS captures a wider range of fire activity multiple times per day.
These are all high-confidence hotspots, meaning satellite algorithms consider them very likely to be actual vegetation fires, not false alarms.
The sharp spike in fire activity highlights how the dry season has intensified in recent weeks, following early signs of trouble in May and June. With most fires detected in peatlands and fire-prone agricultural zones, the July surge raises concerns over worsening air quality, public health and environmental damage.
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Children wear masks due to the toxic smoke from peat land fires, Central Kalimantan, Indonesia. Image by Aulia Erlangga/CIFOR via Flickr (CC BY-NC-ND 2.0).
Peatlands in peril
Many hotspots have also been detected in peatlands, a carbon-rich ecosystem that is often drained in Indonesia for agriculture, leaving them dry, flammable and highly vulnerable to underground fires.
Peatland watchdog Pantau Gambut recorded a staggering 13,608 hotspots across 303 peatland hydrological units in July 2025 alone — nearly sixfold increase from the previous month.
Unlike the government’s fire monitoring system, which only tracks high-confidence hotspots (to reduce false alarms), Pantau Gambut analyzes low- and medium-confidence data as well. “Peat fires often start small and burn underground,” the group said. “Limiting detection to high-confidence signals risks missing early-stage fires.”
The July 2025 figure is more than double the number of peat hotspots in July 2024 and more than four times the July 2023 total. This, despite the 2023 dry season being far more extreme, driven by one of the strongest El Niño events on record, while 2025 is expected to see a milder and shorter dry season.
The sharp increase in hotspots during a time when the dry season is milder shows that the government has failed in addressing the root cause of the annual fire episode, which is unbridled land-clearing activities, said Pantau Gambut advocacy and campaign manager Wahyu Perdana.
The issue of fires, particularly in peatlands, is still largely addressed through reactive measures. Instead of proactively monitoring land-clearing activities and sanctioning companies that violate the law, the government focuses only on fire suppression and emergency operations, Wahyu said.
“As long as peat ecosystems continue to be sacrificed for economic gain, as long as environmental policies remain symbolic and as long as oversight and law enforcement fail to hold corporations accountable, the peat fire crisis will remain an open ecological wound for this nation,” he said.
Transboundary haze returns
The current fire episode is unfolding a decade after Indonesia’s 2015 fire disaster, which burned more than 2.6 million hectares (6.4 million acres) and caused an estimated 100,000 premature deaths, according to independent estimates.
The 2015 fire disaster also caused diplomatic uproar as toxic haze from Indonesia blew across the Malacca Strait to Singapore and Malaysia.
Although 2025’s dry season is expected to be milder, the transboundary haze problem has returned this year.
On July 20, haze from fires in some parts of Indonesia’s Sumatra Island was detected in Malaysia, with five locations recording unhealthy air quality.
The main source of the haze in Malaysia was suspected to be from Riau province, which the government has identified as one of the worst-affected provinces in this year’s fire season.
In late July, fires were spreading rapidly and the burned area in Riau doubled within 24 hours, reaching 1,000 hectares (2,470 acres), according to an official report.
Thick haze has also disrupted daily life in at least two major Indonesian cities: Pontianak in Borneo and Jambi in Sumatra. In both cities, PM2.5 levels have reached “unhealthy” thresholds, and respiratory infections are on the rise.
In Pontianak, air quality monitoring data indicate the air has entered the “unhealthy” category due to high concentrations of PM2.5 fine particles, especially at night, as particulate matter settles closer to the ground, and in the early morning.
Several health care facilities have begun reporting a rise in cases of acute respiratory infections, particularly among toddlers and people with asthma.
The worsening air quality has prompted the mayor of Pontianak, Edi Rusdi Kamtono, to urge residents to limit outdoor activities, especially at night.
Haze has also been detected in the neighboring district of Kubu Raya, 17 kilometers (10.5 miles) away from Pontianak, forcing the local government to close schools to protect children.
In Sumatra, the city of Jambi was reportedly blanketed by haze on July 24. Jambi Governor Al Haris said the smoke is coming not only from burning areas in the province, but also from fires in neighboring Riau province.
A local resident named Diah said she can clearly smell the smoke in the mornings.
“You can really smell the burning when you breathe in through your nose. But it usually clears up by midday,” she said, as quoted by local news Detik.com.
The country’s meteorological agency, BMKG, warned that the worst is yet to come, as most regions in Indonesia, particularly Sumatra and Kalimantan, will only face the peak of the dry season in August, and the dry season is expected to continue until September.
Under these conditions, the risk of forest and land fires is expected to rise sharply, BMKG said.
A NASA satellite image captured September 2015 shows massive plumes of smoke enveloping Sumatra, Borneo, Singapore and southern Malaysia. These fires burned out of control for months and were largely attributed to slash-and-burn clearing of drained peatlands. Image in the public domain.
Government downplays scope
In light of the ongoing fires and warning from BMKG, President Prabowo Subianto chaired a cabinet meeting over the first weekend of August. The main agenda of the meeting was to monitor recent developments in the prevention and handling of forest and land fires.
During the meeting, the president highlighted the significant decline in the area affected by forest and land fires over the past two years, according to Cabinet Secretary Teddy Indra Wijaya.
President Prabowo cited data claiming only 8,955 hectares (22,128 acres) had burned as of August. Yet the Ministry of Forestry had already reported 8,594.5 hectares (21,237 acres) burned between January and May alone — implying that just 360 hectares (about 890 acres) burned in June and July, despite a surge in satellite-detected fires during that period.
Nevertheless, this year’s fire episode is shaping up be the worst in recent years, according to Uli Arta Siagian, the forest and plantation campaign manager at Indonesia’s largest environmental NGO, Walhi.
“Fires in company concessions are worse this year. As of July, the number and intensity of hotspots are already higher than in 2024 — and maybe even 2023,” she said during a recent press conference.
Boy Jerry Even Sembiring, the director of Walhi’s Riau chapter, said the fire episode in the province is looking to be worse this year than in previous years.
“In 2024, Riau had around 370 hotspots for the entire year. By mid-2025, it’s already around 380,” he said.
The meteorological agency warned that August and September would be the most critical period, as dry conditions deepen across fire-prone provinces.
The risk of transboundary haze is rising this year due to growing deforestation, uncertain policy shifts in Indonesia and volatile commodity markets, according to researchers at the Singapore Institute of International Affairs (SIIA), which monitors transboundary haze risk using a green-yellow-red alert system.
“Early in the year, many weather assessments projected a relatively benign haze season,” SIIA chairman Simon Tay said. “However, as the situation evolved, it has become clear that regional fire and haze risks are rising — not just from weather, but from global economic and policy changes. If this had been assessed a month ago, we might have issued a green rating. But the fires and market conditions warrant caution. There is a change in circumstances, and there should be concern.”
With haze thickening and hotspots surging, the coming weeks will test Indonesia’s ability to prevent a full-blown regional crisis — one with echoes of the deadly 2015 disaster.
“If no swift action is taken, 2025 could be worse than previous years,” Boy Jerry said.
This article was originally published on Mongabay under the Creative Commons BY NC ND licence. Read the original article.
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