People in these areas should beware of severe conditions, the department cautioned.
The weather forecast for the next 24 hours is as follows:
Northern region: Mostly cloudy with thundershowers in 40 per cent of the areas and isolated heavy rain; temperature lows of 24-27 degrees Celsius and highs of 34-37°C.
Northeastern region: Mostly cloudy with thundershowers in 60 per cent of the areas and isolated heavy rain; temperature lows of 24-26°C and highs of 32-36°C.
Central region: Mostly cloudy with thundershowers in 30 per cent of the areas; temperature lows of 24-26°C, highs of 34-37°C.
Eastern region: Mostly cloudy with thundershowers in 60 per cent of the areas and isolated heavy rains; temperature lows of 22-26°C, highs of 29-33°C; waves a metre high and 1-2 metres during thundershowers.
Southern region (east coast): Mostly cloudy with thundershowers in 40 per cent of the areas; temperature lows of 23-26°C, highs of 30-36°C; waves a metre high and 1-2 metres during thundershowers.
Southern region (west coast): Mostly cloudy with thundershowers in 40 per cent of the areas; temperature lows of 23-25°C, highs of 30-32°C; waves 1-2 metres high and two metres during thundershowers.
Bangkok and surrounding areas: Mostly cloudy with thundershowers in 30 per cent of the areas; temperature lows of 26-27°C, highs of 32-36°C.