The Niger River flood season: why September and October need watching
The rains are ending over the Sahel, but the water they dropped is still travelling downstream toward Niamey, Lokoja and the delta.
Published September 28, 2026
The rains are ending over the Sahel, but the water they dropped is still travelling downstream toward Niamey, Lokoja and the delta.
At Niamey the Niger rises twice a year. The first, called the red flood because of the sediment it carries, comes in August and September from rain on nearby tributaries in Niger and Burkina Faso. The second, the black flood, starts as rain in the Guinean highlands months earlier and reaches Niamey around December to February after crossing the inner delta in Mali. September and early October are when the red flood usually peaks.
Further downstream in Nigeria, the Niger joins the Benue at Lokoja, and the two peaks can stack on top of each other in September and October. Releases from reservoirs upstream, including the Lagdo dam on the Benue in Cameroon, add to the flow. That combination drove the severe floods of 2012 and 2022 across Kogi, Anambra, Delta and Bayelsa states, and late-season flooding displaced large numbers of people across Niger, Nigeria, Mali and Chad again in 2024.
River floods move slowly, which is an advantage: there is usually warning. Follow the flood outlooks of national hydrological services and the Niger Basin Authority, pay attention when local officials announce dam releases, and treat low-lying riverside land as risky until the levels fall in November. Local rain still matters too. Heavy storms on already saturated ground can flood streets within hours, so keep an eye on the daily rainfall figures in our Sahel Rainfall & Monsoon Watch.