The weather bureau said that the high-pressure area and the cold air mass covering the northeastern and northern regions of Thailand and the South China Sea were weakening. This had caused the monsoon trough to shift upward, passing over the upper southern and eastern regions and affecting the lower southern region, the Gulf of Thailand, and the lower part of the Andaman Sea.
This weather pattern had resulted in convective clouds and heavy rainfall in some parts of the northern, central — including Bangkok and its metropolitan areas — eastern, and southern regions, the department said. People in these areas are advised to be cautious about possible flash floods and potential landslides, especially in hilly areas near waterways.
Waves around 1-2 metres high are expected in the areas in the Gulf of Thailand and the Andaman Sea, or higher in areas with thunderstorms. Small vessels are advised to navigate with caution in areas with thunderstorm, the department said.