The monsoon trough across the Andaman Sea is continuing to cause heavy to very heavy rainfall along the Andman coast, the Thai Meteorological Department (TMD) reported at 5am.
Waves are expected to average two to three metres high, and reach more than three metres high in thunderstorm areas.
People are warned to beware heavy to very heavy rain and accumulated rain causing flash floods and landslides.
Winds are expected to become stronger, with people living in coastal areas to beware strong winds and wind waves hitting the shore.
Operators of large vessels in the area are warned to proceed with caution and avoid sailing in thunderstorm areas. Small boats have been ordered to remain ashore.
The TMD reported 63mm of rainfall across the island yesterday (Oct 18). A further 69mm of rainfall is expected today.
So far 390mm of rainfall has already soaked Phuket this month, the TMD reported, marking that the total rainfall for Phuket for the year now stands at 2,258.9mm