Indonesia Warns of Dangerously High Waves Next July

Maritime Alert Issued for Widespread Coastal Areas

Indonesia’s Meteorology, Climatology, and Geophysics Agency (BMKG) has issued a stark early warning for significant wave heights expected to impact multiple maritime regions across the archipelago. From July 14 to July 17, 2025, sea swells could surge to between 2.5 and 4.0 meters.

Dangerous Swells Predicted

BMKG forecaster Furqon Alfahmi detailed the anticipated conditions. Prevailing winds in Indonesia’s northern waters will generally blow from the southeast to southwest at speeds of 6 to 30 knots. Conversely, southern regions will experience winds predominantly from the east-southeast, also reaching speeds of 8 to 30 knots.

Furqon Alfahmi noted the highest wind speeds are expected in specific locations. These include the northern Malacca Strait, the Indian Ocean west of Aceh extending to the Nias Islands, as well as the Banda Sea and the Arafura Sea. These meteorological patterns are projected to elevate sea levels.

Areas at Risk

The agency forecasts moderate wave heights, ranging from 1.25 to 2.5 meters. These are likely to affect maritime traffic in areas such as the Indian Ocean west of the Nias and Mentawai Islands, the central and eastern Java Sea, the Bali Sea, and the Makassar Strait.

Extremely high waves, measuring between 2.5 and 4.0 meters, are a distinct possibility. Such dangerous conditions are anticipated in the northern Malacca Strait and along the Indian Ocean coastline, stretching from west of Aceh, Bengkulu, and Lampung, down to the southern coast of Banten. Western, Central, and Eastern Java, along with Bali, NTB, and NTT, are also included in this warning.

Safety Advisories Issued

Furqon Alfahmi emphasized the serious implications of these high waves. The potential for high waves in several areas could pose risks to maritime safety, he stated. The BMKG is urging extreme caution for all maritime activities.

“The potential for high waves in several areas could pose risks to maritime safety,”

—Furqon Alfahmi, BMKG Forecaster

The agency strongly advises the public, particularly fishermen utilizing vessels such as fishing boats, barges, and other seafaring craft, to remain vigilant. Coastal communities and individuals working in areas prone to these elevated wave conditions are also being urged to exercise heightened awareness and take necessary precautions.

This forecast echoes previous warnings, such as advisories issued for tourists on Yogyakarta’s beaches, highlighting a persistent concern for coastal safety in Indonesia. In fact, a recent study indicated that extreme weather events, including storm surges, are becoming more frequent globally, with coastal areas facing increasing risks (NOAA, 2023).