Fears are growing for thousands of refugees stuck with next to no shelter in sub-zero temperatures.
In Serbia, hundreds of migrants lined up in the freezing snow at a make-shift shelter in the capital Belgrade to receive a warm meal.
Aid agencies have blasted the authorities for failing to implement emergency measures.
In Greece, the conditions facing refugees are also said to be severe.
On Monday, the European Commission described the situation on several Greek islands as ‘untenable’, heavily criticising the response from Athens.
MSF Sea (@MSF_Sea) January 7, 2017
eu_echo</a> maybe you didn't realize that it's winter and people are freezing in the hotspots where <a href="https://twitter.com/hashtag/EU?src=hash">#EU</a> has trapped thousands? <a href="https://t.co/jpjisINnsX">pic.twitter.com/jpjisINnsX</a></p>— MSF Sea (MSF_Sea) January 9, 2017
“Some people have children. Small, small children. And they need to be warm,” one Afghan refugee said.
The severe arctic weather sweeping most of central and eastern Europe, has been so extreme, parts of the Danube have frozen over, with temperatures dropping below -30.