Jakarta. The Meteorology, Climatology and Geophysics Agency (BMKG) has warned that three tropical systems are currently surrounding Indonesia, raising the risk of heavy rainfall and high waves as the country approaches the peak of its rainy season early next year.

BMKG head Teuku Faisal Fathani told President Prabowo Subianto during a full cabinet meeting at the State Palace on Monday that authorities are monitoring Tropical Cyclone Bakung along with two developing systems known as Tropical Cyclone Seed 93S and Tropical Cyclone Seed 95S. Cyclone Bakung is developing southwest of Lampung, off the southern coast of Sumatra, and is currently moving away from Indonesia. However, BMKG data show the system has strengthened from Category 1 to Category 2.

Faisal said Tropical Cyclone Seroja, which previously caused severe flooding and damage in parts of Indonesia, was classified only as a Category 1 system. Category 1 is the lowest cyclone classification, but it can still generate dangerous weather, including heavy rainfall, strong winds and hazardous sea conditions.

BMKG forecasts that Cyclone Bakung could shift closer to Indonesian territory and said its movement will be closely monitored over the next two to three days. Authorities hope the system will not move nearer, which would increase rainfall intensity across affected regions.

“We will continue to closely monitor its dynamics, with the hope that it does not move closer and affect rainfall levels,” Faisal said.

In addition to Bakung, BMKG is tracking Tropical Cyclone Seed 93S over Bali, Nusa Tenggara and East Java, as well as Seed 95S south of Papua. The presence of these systems is expected to significantly increase rainfall intensity — from heavy to very heavy — and raise the risk of high waves in surrounding waters.

Faisal said BMKG has coordinated with the National Disaster Mitigation Agency (BNPB), regional disaster agencies (BPBD) and the national search and rescue agency Basarnas to ensure preparedness, while urging the public to remain calm.

“We have informed the relevant agencies and asked the public to stay alert but calm, as long as conditions are continuously monitored and preparedness for heavy rain and high waves is maintained,” he said.

Indonesia is not facing the situation alone, Faisal added. The country has been designated by the World Meteorological Organization as a Tropical Cyclone Warning Center, enabling it to play a regional role in monitoring and issuing alerts.

BMKG remains in close communication with meteorological agencies in Australia, Japan and India to assess the development and trajectory of Cyclone Bakung.

“At one point on Dec. 14, Cyclone Bakung briefly reached Category 3, with wind speeds of up to 65 knots. That was extremely dangerous,” Faisal said. “It has since weakened to Category 2, and we hope it will continue to downgrade toward Category 1.”

Weather Modification Underway

As Indonesia prepares to enter the peak rainy season in January and February 2026, BMKG has begun weather modification operations at six locations across Sumatra, Java and Nusa Tenggara to reduce the risk of extreme weather impacts.

Rainfall is expected to rise sharply in southern Sumatra, Java, Bali and Nusa Tenggara, compounded by the influence of Cyclone Bakung and the two developing systems.

The operations involve cloud seeding using sodium chloride to trigger rainfall over safer areas such as open waters, preventing rain-bearing clouds from moving over land. In certain conditions, quicklime, or calcium oxide, is dispersed to break up rain clouds over urban areas, including Jakarta.

“If rain clouds approach land, we seed them so rainfall occurs over the sea or other less risky areas,” Faisal said. “If they are already over Jakarta, we disperse calcium oxide so the clouds break apart and heavy rain does not occur.”

According to BMKG, weather modification efforts can reduce rainfall intensity by 20% to 50%, helping mitigate potential meteorological disasters linked to extreme weather.

BMKG is currently conducting these operations in several regions, including West Java, Central Java, East Java, Bali and Lampung. The agency is also working with BNPB, under the coordination of the Transportation Ministry, to develop an integrated weather information platform for land, sea and air transport.

Faisal urged the public to remain vigilant but not panic, stressing that authorities are continuously monitoring conditions to protect public safety.

“We are working closely with BNPB, BPBD and Basarnas,” he said. “For the public, stay calm, stay alert, and be prepared for heavy rain and high waves.”

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