Disaster Prevention and Mitigation Department's director-general Anucha Mokhawes yesterday warned people living along the coastline and fishermen to keep abreast of weather forecasts and heed warnings.

A southern weather bureau has already warned fishing trawlers against going out to sea for the time being.

Waves will be between two and three metres high today and tomorrow. 

"People living around the Gulf of Thailand from Nakhon Si Thammarat down should be particularly watchful," the bureau's director Kamonsri Seneetantikul said yesterday.

Anucha said his department had already alerted local authorities in Phetchaburi, Prachuap Khiri Khan, Ranong, Phang Nga, Phuket, Krabi, Trang, Satun, Chumphon, Surat Thani, Nakhon Si Thammarat, Phatthalung, Songkhla, Yala, Pattani and Narathiwat about the need to prepare against the weather threats.

"The authorities must also warn people living along the coastline and fishermen," he said.

Fishing trawlers, both small and large, should avoid going out to sea. However, if they received warnings about dangerous waves while out at sea, they should immediately head to a safe area.

"If people receive similar warning while ashore, they should evacuate and move their belongings to a safe place," Anucha said.

Earlier this month, Surat Thani, Nakhon Si Thammarat, Chumphon, Songkhla and Narathiwat were hit by big waves.

Surat Thani Governor Niwat Swasdikaew yesterday said he had ordered sandbag walls to be built along the coastline in risky areas in Tha Chana, Chaiya, Don Sak, Koh Samui and Koh Pha-ngan districts, as well as Tao Island.

"District chiefs have been instructed to arrange patrols and to warn people to be prepared for evacuation," he said.

Dr Traiphop Pongsuwan, a geophysicist at the Prince of Songkla University, believed global warming would bring more storms to the Gulf and big waves along the coastlines.

He said the ongoing phenomenon had never happened before.

"I can't predict anything at this point," he said.