Reuters reports: Up to 700,000 Syrian refugees may flee abroad by the end of the year, the U.N. refugee agency said on Thursday, nearly quadrupling its previous forecast for the exodus from the deepening crisis.

Most faced what was likely to be a bitterly cold winter living in tents with little prospect of returning to their homeland, it said. The agency urged Western donors to help raise nearly $500 million to finance aid operations in four neighbouring countries that have kept their borders open so far.

About 294,000 refugees fleeing 18 months of conflict in Syria have already crossed into Jordan, Iraq, Lebanon and Turkey, or await registration there, the UNHCR said.

“This is a significant outflow taking place, 100,000 people in August, 60,000 in September and at the moment 2,000 or 3,000 per day or night,” Panos Moumtzis, Regional Refugee Coordinator for the U.N. High Commissioner for Refugees (UNHCR), told a news briefing.

“The most important part is the preparing for winter months. The winter period is very harsh in that region,” he said.

The UNHCR’s previous forecast – of 185,000 refugees – was surpassed in August. It had been made in June.