These conditions are brought by the weak high-pressure system over the upper North, the Northeast and the South China Sea, and the easterly and northeasterly winds prevailing across the Gulf of Thailand and the Andaman Sea.
In the South, beware severe conditions that may cause flash floods and overflows, especially along foothills, near waterways and on lowlands. Drivers should exercise more caution, the department warned.
Waves in the Andaman Sea and the Gulf could reach a metre high, or 1-2 metres high if thundershowers are present. All ships should proceed with caution and avoid thundershowers, the department said.