The Disasters Emergency Committee's Southern Africa Food Crisis Appeal, launched in July, has raised £14 million to date.
The latest appeal was a break with tradition in trying to ward off a crisis rather than responding to one. Without emotive TV pictures of dying people, agencies feared that donations would be slow.
However, latest figures show that donations are up on previous committee appeals with average internet donations of £56 and more than £40 for telephone gifts.
Chief executive Brendan Gormley said: "It is difficult to engage public sympathy in a preventative strategy so we were impressed with the public's understanding that if they gave now then they could help prevent a tragedy."
But a recent reassessment of the situation by the UN has added another one million people to those in need of help, taking the total to 15 million. In addition, the committee is concerned that their situation will worsen over the winter.