BMKG Warns of Drier, Longer Dry Season as El Niño Takes Hold Over Indonesia

Indonesia's meteorological agency BMKG is urging governments and communities to prepare for a harsher dry season than usual, with El Niño established in the Pacific and more than half the country's land area forecast to receive below-normal rainfall before the rains return.

In its dry-season update published in June, BMKG said its ENSO index had reached +1.0 by the end of May 2026 — past the agency's threshold for El Niño conditions. Its probability assessment leaves little room for a mild outcome: 100% likelihood the event reaches at least weak intensity, 98% for moderate, and 62% for strong.

The dry-season map

BMKG divides Indonesia into climate zones, known as ZOM, to track the staggered arrival of the seasons across the archipelago. The June update paints a broadly drier picture. 482 zones, representing 56.18% of the country's land area, are predicted to receive below-normal rainfall during the dry season, known locally as the kemarau. A largely overlapping set of 437 zones — 48.77% of land area — faces a dry season that runs longer than normal, with regional durations ranging from three to seven months.

The season is already well under way. BMKG reports that 198 zones (31.60%) entered the dry season in June, with a further 66 zones (7.28%) following in July. The peak is forecast for the July–September window, with August the peak month across most of the country — meaning the driest weeks of an already dry year are arriving now.

Why El Niño hits Indonesia hard

Indonesia sits at the western edge of the Pacific warm pool, the reservoir of hot ocean water that normally fuels the towering rain clouds of the Maritime Continent. During El Niño, that warm water and the rainfall it generates migrate east toward the central Pacific, leaving Indonesia on the subsiding, dry side of the circulation — a mechanism explained in the science of El Niño. Strong events in the past have brought severe drought, agricultural losses and, most visibly, peatland and forest fires whose haze has spread across Southeast Asia.

That history is why BMKG's messaging has leaned heavily on preparedness. In a press release framed around El Niño readiness, the agency flagged the August dry-season peak and called for strengthened preparations against drought and fire impacts — water conservation, early planning for agricultural water allocation, and vigilance in fire-prone peatland provinces.

A regional pattern

Indonesia's dry tilt is one panel in a larger picture. The Philippines' PAGASA issued its first El Niño advisory in June with provinces already in meteorological drought, and Australia's Bureau of Meteorology sees the odds tilted toward a drier winter and spring for its central and east. The World Meteorological Organization's outlook likewise places the broader region on the dry side of the ledger for the coming season — part of the pattern of global impacts that a strong event etches across the map.

For Indonesia specifically, the compounding risk is timing. With El Niño forecast by international agencies to strengthen toward a peak around the end of 2026, the event will be near maximum intensity just as the dry season gives way to the transition months — a period when delayed monsoon onset can extend drought stress well beyond the normal calendar.

Watching the dasarian updates

BMKG monitors ENSO and the Indian Ocean Dipole on a ten-daily ("dasarian") cycle, giving Indonesia one of the most frequent official monitoring cadences of any agency in the region. Those updates will show whether the 62% probability of a strong event hardens over the coming weeks, and when the first zones begin their transition back toward the wet season. Until then, the agency's guidance is straightforward: treat August as the crunch month, and prepare for a kemarau that is both drier and longer than the country is used to.