The advisory follows downpours soaking the island overnight, with wet roads and strong winds making driving conditions dangerous.
From Phang Nga northward, southwesterly winds of 20-40km/h and wave heights reaching up to three metres in thundershowers are forecast for the coming days.
For Phuket southward, the southwesterly winds are expected to reach gusts of 20-35km/h with wave heights averaging about two metres, and above two metres in thundershowers, the TMD said in a release issued to today (July 30).
All small boats were urged to stay ashore.