The fires, concentrated on Indonesia's peatlands in the provinces of Kalimantan, are notoriously difficult to extinguish. Peat fires can burn underground for months, with embers smouldering metres below the surface and flaring up if not completely doused. Crews from Manggala Agni, the national firefighting force, are forced to stand guard overnight to watch for re-ignition.
Andri Susanto, a firefighter on the outskirts of Ketapang in West Kalimantan, described the toll of the extended dry spell. "It's been 60-plus … I've lost count of how many days without rain," he said. "The impact of El Niño has been so severe across Indonesia, and water sources have begun to dry up."
From the air, the provincial capital Pontianak is nearly invisible under a shroud of haze. Smoke from the fires has drifted across borders, contributing to air pollution crises in neighbouring Singapore and Malaysia, reminiscent of the 2015 disaster that cost the region billions of dollars in health and economic damage.
While the area burnt so far is still below the 2015 total, Forestry Minister Raja Juli Antoni warned that the fire season is not over. "The field of struggle is right here in September," he said, as forecasters expect dry conditions to peak this month. The official burn figure does not yet include August data, meaning the final tally will likely rise.