The Nigeria Hydrological Services Agency (NIHSA) has warned of a high risk of riverine flooding in 15 states between September 19 and 25.
In its national flood advisory issued on Friday, the agency said rising river levels could trigger flooding in communities located on floodplains during the seven-day period.
The affected states are Imo, Cross River, Ebonyi, Benue, Anambra, Akwa Ibom, Lagos, Rivers, Edo, Kogi, Taraba, Delta, Bayelsa, Enugu and Abia.
NIHSA identified nine river stations requiring close monitoring, including Obubra, Itigidi and Epento along the Cross River.
The agency said significant populations and critical infrastructure are exposed to flood risks across the affected areas. In Cross River alone, 2,471 communities, 703 schools, 344 health facilities, 145 markets, 453 religious centres and 854 hectares of farmland were identified as being within flood-risk areas.
NIHSA Director-General, Umar Mohammed, urged state and local emergency management authorities, traditional rulers and community leaders to take immediate precautionary measures.
He advised residents in flood-prone communities to move people, livestock and valuables to safer, higher ground where necessary, while activating local early-warning and response mechanisms.
Mohammed also warned residents against crossing flooded roads, bridges or fast-moving water, whether on foot or in vehicles.
He called on relevant authorities to pre-position relief materials, safe drinking water, water-treatment supplies and first-aid materials, while identifying shelters for possible temporary evacuations.
Residents were also advised to clear blocked drainage channels and river outlets where safe, and avoid construction or habitation in vulnerable floodplain areas.
NIHSA said it would continue monitoring river levels and hydrological conditions and issue further advisories as necessary.