According to the agency, strong winds may precede the rains in areas where thunderstorms are likely to occur.
Heavy rainfall and thunderstorms in parts of China have caused severe flooding, raising the death toll to 15 and leaving more than 300 people injured.
The agency anticipated thunderstorms with moderate rains over most parts of the region later in the day.
Germany is bracing for intense summer heat, with forecasters warning that temperatures could approach 40 degrees Celsius by midweek.
NiMet predicted thunderstorms over parts of Delta, Cross Rivers, Akwa Ibom and Bayelsa later in the day.
The Nigerian Meteorological Agency (NiMet) has predicted rainfall and thunderstorms across the country in its latest weather outlook.
NiMet stated that there were slim chances of light to moderate rains over parts of Plateau and Nasarawa states during the morning hours.
According to NiMet, thunderstorms are expected over parts of Kebbi, Adamawa, Taraba, Sokoto, Kano, Katsina, Zamfara, and Kaduna States later in the day.
Reports said most casualties occurred when lightning struck people working in fields and taking shelter under trees during the rain.
Of the four missing people, one woman was rescued, and a man was found dead. The other two individuals remain missing.
