Thundershowers with gusty winds and isolated heavy rains are forecast for the North, the Northeast, the Central and the South.
Waves in the Andaman Sea are expected to rise 2-4 metres high and above four metres during thundershowers. All ships should proceed with caution, while small boats should keep ashore, the department said.
The weather forecast for the next 24 hours:
Bangkok and surrounding areas: Mostly cloudy with thundershowers in 60 per cent of the areas and isolated heavy rains; temperature lows of 25-26 degrees Celsius, highs of 32-36°C.
North: Mostly cloudy with thundershowers in 60 per cent of the region; isolated heavy rains and gusty winds are possible in some areas; temperature lows of 23-26°C, highs of 35-38°C.
Northeast: Cloudy with thundershowers in 60 per cent of the region; isolated heavy rains are possible in some areas; temperature lows of 24-25°C, highs of 32-35°C.
Central: Mostly cloudy with thundershowers in 70 per cent of the areas and isolated heavy rains; temperature lows of 23-25°C, highs of 33-36°C.
East: Cloudy with thundershowers in 70 per cent of the areas and isolated heavy rains; temperature lows of 24-26°C, highs of 28-33°C; waves two metres high and over two metres during thundershowers.
South (east coast): Mostly cloudy with thundershowers in 60 per cent of the areas and isolated heavy rains; temperature lows of 23-26°C, highs of 32-35°C; waves 1-2 metres high and two metres during thundershowers.
South (west coast): Thundershowers in 80 per cent of the areas and isolated heavy rains; temperature lows of 22-24°C, highs of 28-32°C; waves 2-4 metres high and over four metres during thundershowers.