NationThailand-Sept 21
The Thai Meteorological Department (TMD) warned of heavy rain across Thailand on Monday (September 21, 2026), naming 55 provinces in its regional forecasts and also warning Bangkok and surrounding areas. Very heavy downpours are expected in parts of Nakhon Nayok and Prachin Buri. The forecast reported by Thai Post covers the 24 hours from 6am on September 21 to 6am on September 22, 2026, Thailand time. The TMD warned that heavy to very heavy rain, combined with accumulated rainfall, could trigger flash floods and landslides, as well as forest run-off. People on foothill slopes near waterways and in low-lying areas were advised to remain particularly cautious.
The TMD also advised travelers to avoid routes prone to repeated flooding, especially through low-lying areas where water could accumulate over a short period. A monsoon trough continues to cross lower central, upper southern and eastern Thailand, extending towards a strong low-pressure area over the central South China Sea, according to the TMD. The TMD said the high-pressure system, or cool air mass, from China covering upper northern and northeastern Thailand would begin to weaken. A moderate south-westerly monsoon continues to prevail over the Andaman Sea, southern Thailand and the Gulf of Thailand. The TMD forecasts moderate winds and waves in the upper Andaman Sea and upper Gulf of Thailand, with waves around 2 meters high and exceeding 2 meters during thunderstorms. The TMD advised mariners in the Andaman Sea and Gulf of Thailand to proceed cautiously and avoid thunderstorms. Small boats in the upper Andaman Sea should remain ashore. Read more at:
