The Indian National Centre for Ocean Information Services has warned that the coasts of Kerala, southern Tamil Nadu, and the Lakshadweep islands will experience a severe swell surge on Wednesday and Thursday, cautioning coastal communities that seawater could gush into interior areas off the shore.

Swell surge refers to sudden ocean flooding that leads to the gushing in of seawater. These waves originate in deep oceans and travel long distances before hitting the coast as heavy, rolling surges.

“The coastal regions are under a swell surge alert. The low-lying coastal areas are particularly vulnerable. There should be a total suspension of operational and recreational (tourism) activities at the beach or the nearshore regions,” the Hyderabad-based institute suggested.

Authorities have advised small vessels and boats to stay away from the shore for the next 48 hours and to keep a safe distance from one another to avoid collisions.

Why a swell surge now?

On August 13, rough sea conditions originated in the southern Indian Ocean, approximately 10,000 kms away from the Indian coast. This triggered a major swell surge that has been slowly approaching the northern Indian Ocean—the Bay of Bengal and the Arabian Sea.

“The high energy swell was propagating at a speed of about 21 seconds of peak wave period (time in seconds measured between two wave peaks). It is moving towards the Indian coastal regions. The swell surge is expected to hit the southern tip of India in the early hours of 19 August 2026, with the maximum around evening hours and continue till 5.30 pm of August 20,” Indian National Centre for Ocean Information Services said.