Severe flooding in Zimbabwe and Zambia has killed at least 21 people and left thousands homeless in the past month, and threatens to affect farming.
Heavy rain is expected to continue until February
In Mozambique, the authorities have declared a red alert, with rivers rising above "critical" levels.
The rains, which began in early December, have washed away homes and livestock throughout the area.
A spokesman for the Red Cross has said that floods could lead to an increase in malaria and outbreaks of cholera.
More than 1,000 families, mainly in Zimbabwe's Mashonaland Central Province, have had homes and livestock washed away by the rains which began in early December, the UN news agency IRIN News reports
Thousands of homes in the Epworth informal settlement outside the capital, Harare, have collapsed as a result of the rains.
Zimbabwe's Agricultural Technical and Extension Service warned that the rains were adversely affecting farming, with most crops showing signs of nitrogen deficiency, the state-run Herald newspaper reported.
In Zambia's Southern Province, the Magoye River burst its banks, flooding homes and farmland and displacing about 1,000 families, according to IRIN News.
"Aware that the situation may get worse before the end of the rainy season, we have decided to declare a red alert," Mozambique's Minister of State Administration Lucas Chomera said, AP news agency reports.
He said the Zambezi, the Pungue, the Buzi and the Save rivers were all above critical level, and the situation was getting worse as the Cahora Bassa dam on the Zambezi was forced to discharge larger volumes of water.
The minister said about 13,000 people had been evacuated from critical areas and moved to higher ground or to government accommodation centres.
The heavy rain throughout the region has been attributed to the climate phenomenon known as La Nina.