The United Nation's food agency says it needs $70m to maintain helicopter relief flights for Pakistani earthquake survivors throughout the winter.
More than one million quake survivors rely on food aid
The World Food Programme described the quake as the toughest natural disaster it has ever handled.
Millions of people left homeless by the quake are dependant on food aid.
More than 73,000 people were killed in the earthquake eight weeks ago, and almost an equal number were seriously injured, Pakistani authorities say.
The WFP says it only has enough money to last through to January next year.
"We need substantial help," executive director James Morris said. "The helicopters are critical, given the weather, the rugged terrain and our need to pre-position a huge amount of food in places throughout the affected area."
"We have never had a crisis where the use of helicopters was so critical," he added.
Many relief workers say that without a constant supply of food and warm clothes to people in the remote mountainous region, the sub-zero temperatures could result in a second cycle of deaths.
On Friday, senior aid officials in Pakistan warned that most of the tents handed out to survivors would not provide enough protection against the harsh Himalayan winter.
Relief organisations have long been appealing for 'winterised' tents designed to withstand the cold of a Himalayan winter.
Most of the tents given to survivors of the South Asia earthquake in October are not designed for winter conditions, a leading aid agency says.
The International Organisation for Migration (IOM) says the issue of shelter "is becoming more critical".