Bali's Southern Coast Under Tidal-Flood Watch Through September 30

DENPASAR, Bali - September 27, 2026 - Bali’s southern coastline remains under a potential coastal flooding and high-tide warning through September 30, with meteorological authorities urging communities and visitors near the coast to remain alert as sea levels rise around the September 26 full moon.

The warning issued by Balai Besar Meteorologi, Klimatologi dan Geofisika (BBMKG) Wilayah III Denpasar covers the southern coasts of Jembrana and Tabanan, as well as coastal areas of Badung, Denpasar, Gianyar and southern Klungkung.

The alert concerns the possibility of unusually high tides rather than a forecast of continuous flooding across Bali. BBMKG has urged people in affected coastal areas to monitor maritime conditions and prepare for possible impacts.

Full moon raises the tide

According to BBMKG, the principal trigger is the full moon on September 26, when the gravitational effects of the moon and sun reinforce one another and produce higher-than-normal tides.

A BBMKG forecaster said the maximum tidal level during the period could reach approximately 2.8 metres, although the timing of the highest tide differs between locations.

The higher water levels can affect low-lying coastal areas, ports and settlements, as well as activities including loading and unloading, salt production and inland fisheries.

The warning remains active

As of Sunday, September 27, the risk period has not ended.

BBMKG's original warning covers September 26-30, meaning coastal communities and businesses remain within the forecast window for elevated tides.

At the same time, the agency's latest marine forecast shows that conditions at sea also require attention.

For September 27-30, BMKG has classified wave conditions in the waters south of Bali as high, with waves of 2.5 to 4 metres. The warning also covers the southern Lombok Strait, while the Badung Strait is currently in the 1.25-2.5 metre category.

The distinction matters because coastal flooding and wave conditions are related but not identical hazards. A high tide can affect low-lying land, while large waves can create additional risks for boats, water activities and people close to exposed shorelines.

Conditions vary by location

The warning does not mean every beach in Bali will experience flooding at the same time or to the same extent.

BBMKG said the timing of maximum tides varies by location. Its advice is therefore based on coastal exposure rather than treating the entire island as one uniform risk zone.

The latest marine forecasts likewise show differences between individual waters.

For example, the northern Bali Strait is currently forecast to experience relatively low waves, while the waters south of Bali are under a higher wave category.

That variation is important for tourism businesses because conditions at one beach or harbour may be noticeably different from those several kilometres away.

What it means for visitors

For tourists, the warning does not amount to a general closure of Bali's beaches or a suspension of tourism activities.

Instead, the current advice points toward greater caution around low-lying coastal areas, exposed beaches, ports and marine activities, particularly during periods of high tide.

BBMKG has repeatedly asked the public to follow its latest maritime updates through its official channels and the Info BMKG application.

The agency's current marine forecast is also changing as the forecast period advances, making it important for operators of boats, water sports and coastal excursions to check conditions rather than relying on a general assumption about the weather.

A five-day period of increased coastal attention

The September warning is part of a recurring pattern in which astronomical tides can temporarily increase coastal water levels.

This episode began around the September 26 full moon and is expected to remain relevant through September 30.

For Bali's coastal communities, the immediate concern is possible water intrusion in vulnerable low-lying areas.

For visitors, the more practical issue is the combination of higher tides and elevated wave conditions in southern waters.

The message from BMKG is therefore one of vigilance rather than alarm: conditions are not uniform across Bali, but the southern coast remains within an officially identified period of elevated coastal risk until the end of September.