The warning was issued by Southern Western Meteorological Center Director Wirot Liucharoensap at 5am.
The weather warning is marked to be in effect today through Saturday (Oct 1).
Noru had been downgraded to a tropical depression, Mr Wirot noted.
Regardless, he cautioned ,”With the relatively strong southwest monsoon prevailing over the Andaman Sea, the southern west coast is expected to experience heavy to very heavy rainfall in some areas in the provinces of Ranong, Phang Nga, Phuket, Krabi, Trang and Satun.
“People in the area should beware of heavy to very heavy rain and accumulated rain. This may cause flash floods, especially near hillside slopes, waterways and lowland areas, during the said period,” he added.
“Wind waves in the Andaman Sea will be strong,” Mr Wirot cautioned. Waves are expected to reach two to three metres in height, and more than three metres in thunderstorm areas.
“Sailors are advised to be careful in navigation and avoid sailing in thunderstorm areas. Small boats should refrain from leaving the shore,” Mr Wirot advised.
People were asked to closely follow weather reports during the period.
The weather warning issued this morning followed Phuket Governor Narong Woonciew joining a teleconference with disaster officials in Bangkok yesterday, asking for all emergency workers to be on 24-hour standby as a precaution.