Southeast Asia haze risk rises as El Niño targets August and September
Indonesia’s active wildfire season has become a regional haze risk, with fires burning across Sumatra, Kalimantan and East Java as the dry season intensifies. The ASEAN Specialised Meteorological Centre activated Level 2 for the Southern ASEAN region on Aug. 3, warning that persistent dryness, smoke and wind patterns could increase the chance of haze crossing national borders.
Level 2 does not mean a severe region-wide haze emergency is underway. Under ASMC’s alert system, it means the risk of transboundary haze is increasing. The center considers hotspot activity, observed smoke, persistent dry weather and prevailing winds when assigning the alert level.
Fires are already affecting communities
Associated Press reported that nearly 48,900 hectares of peatland had burned across six fire-prone Indonesian provinces as of Aug. 10, citing Indonesia’s National Disaster Management Agency. AP reported that West Kalimantan, on Borneo, had the largest affected area.
In Pontianak, the West Kalimantan capital, the city’s Education and Cultural Office ordered schools to suspend in-person classes on Aug. 10 after air quality deteriorated to unhealthy levels. AP also reported that satellite imagery showed smoke drifting from West Kalimantan into neighboring Malaysia on several days during August.
The effects were localized rather than uniform across Indonesia or Malaysia. In Sarawak, Malaysia’s Department of Environment recorded 11 areas with unhealthy air early Aug. 11, and the state government told schools in those areas to halt outdoor activities, according to AP. Smoke movement depends on the location and intensity of fires, wind direction and local weather.
East Java provides another example of the pressure on Indonesian authorities. A wildfire in Bromo Tengger Semeru National Park had affected nearly 900 hectares by Aug. 11, according to AP. Firefighters had mostly contained the blaze but were still working on two remaining hotspots, while the Mount Bromo tourist area remained closed.
Why August and September matter
Indonesia’s Meteorology, Climatology and Geophysics Agency, known as BMKG, said wildfire risk began increasing in July and was expected to peak in August and September 2026. It identified Riau, West Kalimantan, Central Kalimantan, South Sumatra and Jambi as priority provinces for intensified monitoring and oversight.
BMKG said its preventive measures include monitoring hotspots, wetting vulnerable or previously burned peatlands, maintaining water supplies and carrying out weather-modification operations based on meteorological conditions, groundwater levels in peat areas and fire data. AP separately reported that Indonesia had deployed more than 35 aircraft, including water-bombing helicopters and patrol planes, across Sumatra and Borneo.
What the ASEAN alert is measuring
ASMC’s Aug. 3 alert said satellite surveillance detected moderate smoke haze from clusters of hotspots in western and southern Kalimantan, along with some smoke plumes from southern Sumatra. NOAA-20 detected 185 and 371 hotspots in Kalimantan on Aug. 1 and Aug. 2, respectively, and 26 and 11 hotspots in Sumatra on those dates.
ASMC warned that the situation could deteriorate if dry weather persisted and El Niño conditions continued strengthening. The alert is a regional risk assessment, not a guarantee that every location in Southeast Asia will experience cross-border haze.
El Niño adds a climate risk factor
ASMC’s seasonal outlook, updated July 20, said El Niño conditions were expected to continue through the second half of 2026 and were very likely to become strong in August and September. The center says El Niño typically produces drier-than-average rainfall conditions across much of Southeast Asia, including parts of the Maritime Continent during the June-to-August period.
That forecast does not make El Niño the sole cause of the fires. Ignition, land clearing, plantation practices, peatland management and enforcement are separate questions. El Niño is better understood as a climate factor that can dry vegetation and peat, extend fire-weather conditions and make suppression more difficult. ASMC also cautions that the effects vary by location and season.
Why peat fires can become a cross-border problem
Peat fires can continue smoldering below the surface after visible flames disappear and can reignite if they are not fully extinguished. They also produce dense smoke. When prevailing winds carry that smoke toward neighboring countries, a fire concentrated in one Indonesian province can create air-quality problems across a border.
That does not mean all of Indonesia, Malaysia or Southeast Asia is experiencing unhealthy air. Residents should rely on local air-quality readings and health advisories rather than regional generalizations. The World Health Organization’s air-pollution guidance explains the general health importance of reducing exposure to polluted air, but it is not a measurement of current conditions in Pontianak, Sarawak or any other affected location.
What residents, schools and travelers should watch
People with asthma or other respiratory conditions, older adults and children may need to take extra precautions when local smoke levels worsen. Schools and outdoor employers may restrict activities, while parks and tourist sites can close. Travelers and transport operators should monitor local visibility, air-quality advisories and official operating notices; the sources reviewed here do not establish a region-wide transport disruption.
The next important signals are hotspot counts, rainfall, wind direction, local air-quality readings and decisions by schools, parks and public-health agencies. A temporary fall in hotspots or a short rain event would not necessarily end the season’s risk if peat continues smoldering and dry conditions and El Niño are forecast to persist.
Sources
- ASEAN Specialised Meteorological Centre alert, Aug. 3, 2026
- Indonesia BMKG preparedness update, July 28, 2026
- Associated Press wildfire report, Aug. 11, 2026
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