Nature Climate Change, Published online: 23 October 2026; doi:10.1038/s41558-026-02772-0Extreme southward swings of the South Indian convergence zone (a major source of rainfall across southern Africa) can trigger devastating floods. Climate-model projections indicate that these swings might occur twice as often in the twenty-first century as in the previous century and produce more intense rainfall, owing to an increased land–sea temperature contrast and poleward intensification of atmospheric circulation.