Residents in Tanzania and Mozambique are bracing for the touchdown of Cyclone Kenneth – which is barrelling towards land with winds of 205km/h (125mph) and torrential rain.
Communities in the southern Tanzanian region of Mtwara and in northern Mozambique are being warned to seek higher ground and shelter.
UN officials say they fear it could mean a “humanitarian catastrophe”.
Last month, Cyclone Idai caused hundreds of deaths in the region.
More than 900 people died when the storm brought devastation to Mozambique, Malawi and Zimbabwe.
At least three million people were left in need of humanitarian assistance.
The latest system is expected to hit further north than Idai, forecaster say.
Kenneth, an intense tropical cyclone, is expected to make landfall on the north coast of Mozambique on Thursday evening.
Forecasters warn it is likely to be slow-moving, meaning heavy rain is expected to fall on the area for several days.
Flights have already been cancelled and schools closed as Mozambique braces for the storm to hit.
Its violent winds and rains hit the island nation of Comoros overnight. Authorities there say the storm killed at least three people as it swept through.
The country’s two main islands saw power outages and trees downed in high winds, Reuters news agency reports.
