TEMPO.CO, Jakarta - Indonesia’s Meteorology, Climatology, and Geophysics Agency (BMKG) has warned that the new moon on December 20, 2025, could raise maximum sea levels and trigger coastal flooding in several parts of the country.
BMKG’s Director of Maritime Meteorology, Eko Prasetyo, said observations of sea levels and tidal forecasts indicate a heightened risk of tidal flooding across numerous coastal regions.
According to Eko, affected areas include the coasts of Aceh, North Sumatra, West Sumatra, Jambi, the Riau Islands, the Bangka Belitung Islands, Lampung, Banten, Jakarta, West Java, Central Java, East Java, West Nusa Tenggara, and several other provinces.
“Coastal flooding could disrupt activities in and around ports and coastal communities, including cargo loading and unloading, daily life in coastal settlements, as well as salt farming and inland fisheries,” Eko said in a written statement on Wednesday, December 17, 2025.
He urged residents in vulnerable areas to remain alert and prepare for potential impacts during peak tides, while also closely monitoring maritime weather updates issued by BMKG.
Below are the locations and periods with potential tidal flooding:
- Aceh Coast
Meulaboh, Bireuen, and Lhokseumawe from December 21–26, 2025
- North Sumatra Coast
Medan Belawan, Medan Labuhan, and Medan Marelan from December 19–23 and on December 31, 2025
- West Sumatra Coast
Mentawai Islands from December 18–22, 2025
- Jambi Coast
Berhala Strait from December 20–24 and December 30–31, 2025
- Riau Islands Coast
Batam from December 21–25, Dabo Singkep from December 19–27, Karimun from December 18–26
Bintan from December 21–25, Tanjung Pinang from December 19–26, Natuna from December 22–23, Anambas from December 19–22, 2025.
- Bangka Belitung Islands Coast
Bangka and Belitung from December 19–26, 2025
- Lampung Coast
Bandar Lampung, Tanggamus, South Lampung, Pesawaran, East Lampung, and West Lampung from December 21–22, 2025
- Banten Coast
Northern Tangerang and Northern Serang from December 20–26
Western and Southern Pandeglang from December 23–24
Southern Lebak from December 21–28, 2025
- Jakarta Coast
Kamal Muara, Kapuk Muara, Pluit, Ancol, Kamal, Marunda, Cilincing, Tanjung Priok, Kalibaru, Muara Angke, and Penjaringan from December 16–24, 2025
- West Java Coast
Northern coast (Subang, Indramayu, Cirebon) on December 15 and December 27–31
Southern coast (Cianjur, Sukabumi, Garut, Tasikmalaya, Pangandaran) from December 20–31, 2025
- Central Java Coast
Semarang, Demak, Pekalongan City and Regency, Batang, Kendal, and Jepara from December 19–30
Brebes, Tegal City and Regency, and Pemalang on December 15 and December 21–30, 2025
- East Java Coast
Surabaya Port from December 18–24, 2025
- West Nusa Tenggara Coast
Lombok from December 17–25
Bima from December 16–24, 2025
- North Kalimantan Coast
Tarakan waters from December 20–22, 2025
- South Kalimantan Coast
Barito Kuala, Banjar, Banjarmasin, and Tanah Laut from December 19–28
Kotabaru and Tanah Bumbu from December 18–26, 2025
- West Kalimantan Coast
Pontianak City and the Kapuas River from December 19–26, 2025
- Central Kalimantan Coast
Kotawaringin River from December 22–26
Sampit Bay from December 21–28, 2025
- North Sulawesi Coast
North Bolaang Mongondow, Bolaang Mongondow, South Minahasa, Minahasa, Tombariri, Mandolang, and Manado from December 17–31
North Minahasa from December 18–24
Bitung and Kema from December 20–22
Sitaro Islands from December 19–24
Talaud Islands from December 20–23
Sangihe Islands from December 17–25, 2025
- West Sulawesi Coast
Simboro and Mamuju on December 21, 2025
- Maluku Coast
Ambon and Central Maluku from December 17–31
East Seram from December 17–25 and December 27–31
Aru Islands from December 21–23 and December 29–31, 2025
- South Papua Coast
Merauke, Naukenjerai, and Semangga from December 22–26, 2025
BMKG continues to advise coastal communities, port authorities, and maritime operators to remain cautious and stay informed through official weather updates.
Read: 4 BMKG Channels to Track Indonesia's Weather Before Year-End Holidays
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