BMKG Warns of High Waves up to 4 Metres in North Sumatra Waters Until 28 May 2026

The Indonesia Meteorology, Climatology, and Geophysics Agency (BMKG) has warned the public and stakeholders to be cautious of potential waves up to four metres in parts of North Sumatra (Sumut) waters.

Rizky Ramadhan, a forecaster at BMKG’s Belawan Maritime Meteorological Station, said on Sunday that waves between 2.5 and 4 metres could occur in North Sumatra waters from 25 to 28 May 2026.

He specified that the high waves are likely in the western waters of Nias Islands, the Indian Ocean west of Nias Islands, and the western waters of Batu Islands.

“These conditions must be monitored as they could disrupt shipping,” he added.

Wind patterns across northern Indonesia generally move from southeast to northwest at 6-22 knots, while in southern Indonesia, they shift from northeast to southeast at 5-29 knots.

Fishermen are advised to exercise caution when wind speeds reach 15 knots and waves are 1.25 metres high. Similarly, small boats should be alert if winds hit 16 knots and waves reach 1.5 metres.

“Ferries must also be cautious when winds reach 21 knots and waves are 2.5 metres high,” Ramadhan said.