West Africa is experiencing more frequent and intense extreme weather, especially heavy rains and flooding. These events threaten rain-fed farming and the well-being of millions across the region. One major factor influencing these extremes is the Madden-Julian Oscillation (MJO), a tropical weather pattern that moves from west to east and affects rainfall every few weeks. In this study, we examined how the MJO influences extreme rainfall in West Africa, using both observed data and simulations from 23 global climate models.

We found that the MJO has a clear impact: rainfall increases significantly during certain phases and decreases during others. The effect is especially strong near the Gulf of Guinea, where moisture brought in by the MJO leads to more intense and frequent rainfall.

Some climate models captured these patterns well, but others showed major differences, particularly in estimating the chance of extreme events. This often depends on how accurately the model simulates the MJO’s movement.

These results highlight the need to improve how climate models represent tropical weather systems like the MJO. Doing so could enhance early warnings for extreme weather and lead to more reliable climate predictions for West Africa.