The Meteorological Department issued its sixth weather warning on Thursday, cautioning residents across 43 provinces to brace for heavy to very heavy rainfall and potential flash floods until September 27.
The alert covers parts of the north, the northeast, the central plains, including Bangkok and surrounding provinces, as well as the east and the south.
According to the department, a strong low-pressure system over Cambodia is moving across the southern part of the northeast, eastern and central regions, as well as the Greater Bangkok area, along an active monsoonal trough stretching across northern Thailand.
At the same time, the strengthening southwest monsoon is bringing unsettled conditions over the Andaman Sea, Thailand and the Gulf of Thailand.
Authorities warned the public of the dangers from accumulated continuous rainfall, which could trigger flash flooding and runoff, particularly in low-lying areas and slope bases near natural waterways.
Commuters are advised to avoid flood-prone routes where temporary waterlogging is likely.
Sea conditions in the northern Andaman Sea and northern Gulf of Thailand are expected to deteriorate, with waves reaching 2 to 3 metres and exceeding 3 metres during thunderstorms. In the southern Gulf and southern Andaman Sea, waves will average around 2 metres and rise higher during storms.
Mariners are urged to navigate with extreme caution and avoid stormy areas, while small boats in the northern areas of the Gulf and Andaman Sea should remain ashore through Sunday.
Residents are advised to plan travel carefully and monitor official weather updates for safety.
