The UN has warned it is running out of funds to help the 350,000 people in Mozambique in need of food aid.
The World Food Programme (WFP) told the BBC that seven of the country's 11 provinces face an acute problem because of poor harvests.
Central and southern regions have had less than half their normal rainfall since last October.
Now heavy downpours this week have caused flooding, killed 25 people and left thousands of others homeless.
The BBC's Jose Tembe in the capital, Maputo, says crops from central Sofala province are also under threat from locusts which have invaded the area in the last few days, worsening the impact of torrential rains.
Relief authorities fear that flooding could devastate the region by March, the peak of the rainy season.
The worst flooding in Mozambique's living memory was in 2000 when about 700 people died and half a million others were made homeless.
The WFP's Peter Transburg said the agency needed $8.5m (£5.8m) to purchase food aid locally for the destitute.
The money is needed to buy nearly 11,000 tonnes of cereals, beans and cooking oil to supplement household reserves and help families cope with high food prices.
"The situation is quite dire for a quarter of a million people who lost crops last year and lost homes, in some cases, in the floods," he said.
"At the moment our pipeline for food, which is our food supply, is going to break as soon as February."
Convincing donors to give aid was hard given on-going crises like that in neighbouring Zimbabwe, he said.
"But it makes us have to speak a bit louder about our circumstances because it is not so obvious to the donors and to the rest of the world that in fact there still a relief need in Mozambique."