Aid groups and officials in Malawi say at least 60 people have died as a result of the destruction caused by tropical storm Freddy.
Mobile phone footage shows homes with their roofs torn off and extremely dangerous, fast-flowing water in urban areas.
The full impact is not yet clear as some areas have been cut off.
The storm struck Mozambique as a cyclone on Sunday – for the second time in a less than a month.
The authorities there say they so far know of six deaths in the port city of Quelimane.