The International Organization for Migration announced on Friday that 48,000 refugees crossed into Greece by sea this week - the highest number of weekly arrivals so far this year.
"Despite deteriorating weather conditions, approximately 48,000 refugees and migrants crossed from Turkey to the Greek islands, or about 9,600 migrants and refugees in each of the past five days," the IOM said in a statement.
Greece is struggling to cope with the massive influx through its islands bordering with Turkey, which is the result of increasing violence in Iraq, Syria and Afghanistan.
According to the expectations of Greek officials, the European refugee crisis could be worsened with the new arrivals from Turkey, Jordan, and Lebanon.
The UN refugee agency (UNHCR) said an offensive launched by Syrian government troops and their allies, backed by Russian jets, in the south of Aleppo a week ago has displaced nearly 50,000 people so far.
Turkey also sped up preparations on the eve of the massive influx.
The Turkish government and aid agency officials said it is not fully clear yet how many refugees from Aleppo and the surrounding areas will move into Turkey.
Vice president of the Turkish Red Crescent, Kerem Kinik said, "We are preparing our teams for a new wave. We have mobile kitchens, food packaged."
President Tayyip Erdogan also said on Thursday that Turkey has "strong indications" of a new wave of migration from Aleppo, emphasising that a "safe zone" in Syria is vital to protect civilians.
Turkey has opened its doors to nearly two million refugees fleeing from conflict areas in Syria and Iraq mostly to reach wealthier European countries which have better conditions.