According to the Thai Meteorological Department, a severe weather advisory has been issued covering September 9 through 13, 2026, warning of heavy to very heavy rainfall across multiple regions due to an advancing cold mass and a strong monsoon trough.
The initial phase of the weather system brings intense downpours to parts of northern, northeastern, central, and eastern Thailand. The Meteorological Department reports that these conditions are driven by a high-pressure or cool air mass extending down into Vietnam and upper Laos. This weather pattern pushes the monsoon trough downward to lie across the northern region, upper central region, and northeastern region, while a moderate southwest monsoon prevails over the Andaman Sea, Thailand, and the Gulf of Thailand.
Regional Weather Shifts and Bangkok Impact
Following the initial storms, weather conditions are projected to shift across the country from September 10 to 13. Lower northeastern areas, the central region including Bangkok and its vicinity, the eastern region, and the southern region will continue to experience continuous rain with isolated heavy to very heavy downpours. Meanwhile, rainfall activity is expected to decrease in the northern region and upper northeastern region.
This subsequent shift occurs as a high-pressure system from China moves to cover upper northern and upper northeastern Thailand. The Meteorological Department notes this will push the monsoon trough further down to span the lower central region, lower northeastern region, and eastern region, feeding directly into a strong low-pressure cell over the central South China Sea. Simultaneously, the southwest monsoon covering the Andaman Sea, the southern region, and the Gulf of Thailand will strengthen.
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Safety Precautions and Tropical Storm Monitoring
Residents across upper Thailand and the upper southern region must remain alert to the dangers of heavy rainfall and accumulated water. The Meteorological Department warns that these conditions could trigger flash floods and forest runoffs, particularly in foothills near flowing waterways and low-lying areas. Travelers are advised to avoid routes prone to recurring flooding, especially low-lying sectors that may face short-term water accumulation.
Looking ahead, a low-pressure cell situated over the central South China Sea shows potential to intensify into a tropical storm between September 11 and 13. The Meteorological Department urges the public to monitor weather forecasts continuously throughout this period as the situation develops.
Frequently Asked Questions
What dates does the Meteorological Department weather advisory cover?
The advisory is in effect from September 9 to September 13, 2026.
Which areas will experience continuous rain and heavy downpours from September 10 to 13?
The lower northeastern region, the central region including Bangkok and its vicinity, the eastern region, and the southern region will continue to see continuous rain and heavy to very heavy rainfall in some areas.
What system is projected to develop in the South China Sea?
The low-pressure cell currently located over the central South China Sea has the potential to intensify into a tropical storm between September 11 and 13.
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