An estimated 31,244 migrants have braved the deadly boat crossing over the Mediterranean Sea to Greece in the first 16 days of this year.

The shocking statistic represents 21 times the number of migrants who crossed during the same period in January 2015, according to the International Organisation for Migration.

It is expected that the number of new arrivals to Greece is likely to exceed the 853,650 migrants who crossed over to Greece by sea last year.

An estimated 31,244 migrants have braved the deadly boat crossing over the Aegean Sea to Greece in the first 16 days of this year

Almost half (48%) of the migrants who have made the journey are Syrian nationals, fleeing the longstanding war in their homeland.

607 migrants have been rescued off the Italian coast, with many of the migrants trying to make the sea voyage from Libya.

The number of migrants heading to Italy has fallen since 2014, when 170,100 men, women and children managed to cross to Italy.

In contrast to the large volume of Syrians crossing to Greece, many of the migrants hoping to reach Italy are African. Nigerian, Eritrean and Somali refugees make up most of the new arrivals.

It is expected that the number of new arrivals to Greece is likely to exceed the 853,650 migrants who crossed over to Greece by sea last year

The number of migrants heading to Italy has fallen since 2014, when 170,100 men, women and children managed to cross to Italy

Children were coming ashore on the Greek island of Lesbos wearing only T-shirts and soaking wet after travelling on unseaworthy rubber dinghies, the charity Save the Children said in a statement

Thousands of refugee children travelling along the migration route through Turkey and southeastern Europe are at risk from a sustained spell of freezing weather in the next two weeks, according to the United Nations.

The U.N. weather agency said it forecast below-normal temperatures and heavy snowfall in the next two weeks in the eastern Balkan peninsula and the Middle East.

'Many children on the move do not have adequate clothing or access to the right nutrition,' said Christophe Boulierac, spokesman for the U.N. children's agency UNICEF.

Asked if children could freeze to death, he told a news briefing: 'The risk is clearly very, very high.'

Temperatures were forecast to drop to -20 degrees Celsius in Presevo in Serbia and -13 degrees on the Greek border with Macedonia

607 migrants have been rescued off the Italian coast, with many of the migrants trying to make the sea voyage from Libya

The U.N. weather agency said it forecast below-normal temperatures and heavy snowfall in the next two weeks in the eastern Balkan peninsula, Turkey and the Middle East

Children were coming ashore on the Greek island of Lesbos wearing only T-shirts and soaking wet after travelling on unseaworthy rubber dinghies, the charity Save the Children said in a statement.

'Aid workers at the border reception centre in Presevo say there is six inches of snow on the ground and children are arriving with blue lips, distressed and shaking from the cold,' it said.

It said temperatures were forecast to drop to -20 degrees Celsius in Presevo in Serbia and -13 degrees on the Greek border with Macedonia.

Last year children accounted for a quarter of the one million migrants and refugees arriving across the Mediterranean in Europe, Boulierac said.