The southerly and southeasterly winds bring the humidity from the South China Sea and the Gulf of Thailand to the lower Northeast and the East, while the moderate high-pressure system arrives from southern China.
The system is expected to reach the Northeast of Thailand and the South China Sea by Monday night. The heat low remains over the upper country with hot and hazy conditions during the day.
The storm tends to occur under these conditions.
People are advised to stay safe due to the severe conditions by keeping off outdoor places, large trees and unsecured billboards. Farmers should prevent damage to crops, the department said.
The forecast for the next 24 hours:
Bangkok and its vicinity: Hazy day; minimum temperature 24-26°C, maximum 33-37°C; southerly winds 10-20 km/hr.
North: Cool in the morning; hot day with haze; minimum temperature 16-23°C; maximum 33-39°C winds; westerly winds 10-20 km/hr.
Northeast: Hot day with haze; isolated thunderstorms and gusty winds; minimum temperature 18-24°C, maximum 35-38°C; cold on mountaintops with minimum temperature 12-15°C; easterly winds 10-20 km/hr.
Central: Hot day with haze; minimum temperature 21-24°C, maximum 36-38°C; westerly winds 10-20 km/hr.
East: Hot day with haze; isolated thunderstorms and gusty winds; minimum temperature 23-25°C, maximum 32-38°C; southerly winds 10-30 km/hr; waves below a metre high.
South (east coast):
Partly cloudy; minimum temperature 22-25°C, maximum 31-36°C; easterly winds 15-30 km/hr; waves about a metre high
South (west coast):
Partly cloudy; minimum temperature 21-24°C, maximum 32-36°C; northwesterly winds 10-30 km/hr, waves below a metre high.