On 9 September 2026, Thailand is expected to experience an increase in rainfall, with widespread heavy rainfall and isolated very heavy rainfall in some areas. The impacts are initially expected over the Northeastern region, before extending to the rest regions. This is due to a high-pressure system spreading over southern China, which will move further down to cover upper Vietnam and upper Laos. As a result, the monsoon trough will shift southward to pass through the North, the Upper Central, and the Northeast, while the moderate southwest monsoon prevails over the Andaman Sea, Thailand and the Gulf. Thereafter, during 10 - 13 September 2026, the high-pressure system from China will extend to the upper North and upper Northeast of Thailand leads to the monsoon trough will subsequently shift southward across the lower Central, the eastern region and the upper South into the active low pressure cell over the central South China Sea. Meanwhile, the southwest monsoon is expected to strengthen. Less rain is likely in the upper North and upper Northeast, while rainfall will increase over the Central region, including Bangkok and vicinity, the East, and the South, with heavy to very heavy rainfall are possible in some areas.