About 55,000 Syrians are living in the Za'atari camp in northern Jordan.
The storm that hit the region this week, packing rain, snow and bitter cold, overwhelmed drainage in the camp leaving tents mired in mud, UNICEF said in a release Thursday. Much of the camp was flooded.
"The next 72 hours will be critical test of our ability to meet the basic needs of children and their families at Za'atari," said Dominique Hyde, UNICEF's representative in Jordan. "Alongside the government of Jordan and our other partners, we are doing everything possible to ensure services are maintained and that children stay warm and dry."
UNICEF has handed out emergency supplies, including heaters, warm clothing and sleeping mats to replace water-soaked mattresses.
The United Nations estimates more than 10,000 Syrians have relocated to Jordan since Jan. 1 as fighting in Syria continues for the 23rd straight month.
U.N. Secretary-General Ban Ki-moon plans to chair a conference in Kuwait Jan. 30 to raise international relief funds for Syrians caught in the civil war.