In an urgent warning issued at 5am, the department said Ranong, Phang-nga, Phuket, Krabi, Trang and Satun would be hit with torrential rain unleashed by a low-pressure system over the lower South that moved into the Andaman Sea
The waves in the Andaman and the lower Gulf are likely to be 2 meters high but higher in areas experiencing in thunderstorms.
All ships have been advised to proceed with caution and small boats should keep ashore.