The wet season in the archipelago starts this month and ends in April 2026, Meteorology, Climatology and Geophysics Agency (BMKG) head Dwikorita Karnawati said in a news conference.

The peak wet season will begin in November and December this year for Sumatera and Borneo islands, she said. Meanwhile, Java, Sulawesi, Maluku and Papua islands will experience the peak season from January to February 2026.

"We must be cautious because the peak of the wet season is quite long and happens in almost all areas in Indonesia," she said as reported by Reuters.

"The risk of floods is high between November this year and February next year," said BMKG deputy fo meteorology Guswanto.

The agency also warned of extreme rainfall in a short period of time. Dwikorita said certain areas could see the equivalent of a month's rainfall in a single day.

Bali had experienced the equivalent of a month's rainfall in two days over the last few days, the agency said.

Heavy rains on Tuesday and Wednesday caused floods in Bali's capital Denpasar and six other regions, killing at least 19 people and forcing the evacuation of more than 500 people.

"We must anticipate what will happen in the peak of wet season because of what happened in Bali" before the peak, Dwikorita said.

The weather agency had previously predicted a shorter-than-expected dry season this year due to higher-than-normal precipitation.