Indonesia’s most dangerous fires are burning underground

Indonesia’s dangerous peat fires are surging early in the 2026 fire season as a strengthening El Niño and severe drought dry out wetlands that can burn underground for months. These slow smoldering fires are especially destructive because they release far more fine particles and several pollutants than typical tropical forest fires, while thick smoke can make them difficult for satellites to detect. Indonesia’s most dangerous fires are burning underground.

Instead of racing through trees and vegetation, these fires smolder through dried wetland soils and large deposits of peat, often continuing underground at relatively low temperatures. That makes them extremely difficult to extinguish and exceptionally polluting. By one estimate, peat fires produce three times more fine particulate matter than other tropical forest fires, along with five times more sulfur dioxide, three times more organic carbon, and twice as much methane and carbon monoxide.

Satellite Images Reveal Indonesia’s Fire Season Indonesia’s 2026 fire season was already underway when the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard NASA’s Aqua satellite captured an image of the region on September 1, 2026. On the annotated map, each red dot represents a "fire detection." This means the satellite sensor and an algorithm identified a pixel containing thermal anomalies associated with fire. A single fire can produce multiple detections.