Rizky Pradita Ananda, Jakarta – The Meteorology, Climatology, and Geophysics Agency (BMKG) has warned of a possible weak La Nina forming toward the end of 2025, which could lead to increased rainfall across parts of Indonesia.

While the El Nino – Southern Oscillation (ENSO) outlook remains largely neutral throughout the year, BMKG noted that a few global climate models are indicating signs of a weak La Nina emerging later in 2025.

"The potential La Nina condition may contribute to higher rainfall intensity in several regions across Indonesia," BMKG said in an official statement on Monday.

According to BMKG's monitoring, the start of the rainy season will vary across the archipelago. About 333 seasonal zones, or roughly 47.6 percent of the country, are expected to enter the rainy season between September and November 2025. Some parts of Sumatra and Kalimantan, however, have already seen early rainfall before September.

The rainy season will gradually expand toward the southern and eastern regions, with most areas expected to experience their first significant rains in September through November.

Compared to historical patterns, the 2025-2026 rainy season is forecast to begin earlier than usual in 294 seasonal zones, around 42.1 percent of Indonesia.

Rainfall accumulation during this period is expected to remain within normal ranges, meaning conditions are unlikely to be significantly wetter or drier than average.

BMKG also predicts that the peak of the rainy season will occur between November and December 2025 in western Indonesia, and between January and February 2026 in the southern and eastern parts of the country.

The agency cautioned that this year's rainy season may last longer than usual, urging the public to remain alert to potential weather-related hazards.

Source: https://jakartaglobe.id/news/expect-more-rain-indonesia-could-face-weak-la-nina-by-late-202