The Meteorology, Climatology and Geophysics Agency (BMKG) says El Niño is at "very strong" intensity. At a press conference on the rainy-season outlook on 22 September 2026, BMKG put the Niño 3.4 sea-surface temperature anomaly at +2.83 in late August. Together with the Indian Ocean Dipole (IOD), this worsens and prolongs the dry spell, so the rainy season arrives late and is shorter.
Distribution
A total of 529 season zones (ZOM), or 61.08 percent of Indonesia's land area, are expected to see a rainy season that starts later than the climatological average. Eleven zones (1.12 percent) start earlier and 26 zones (2.15 percent) are on time. The rainy season arrives in stages from November and December 2026, peaking from December 2026 to February 2027. Its duration is shorter than normal in 482 zones (51.90 percent).
Current conditions
At the time of the announcement, 556 zones (61.91 percent of land area) were still in the dry season. The number of days without rain exceeded 60 at many observation points across 25 provinces, with the longest at 131 days in Bantul.
Advice
BMKG urged the public to stay alert to drought and forest and land fires in September–October, and to prepare drainage and evacuation readiness for floods and landslides at the start and peak of the rainy season.