Reuters
The crisis - spurred largely by Syria's civil war - has caused numerous political spats, leading to the construction of walls around certain countries and the closing of borders between others.
Now, a new obstacle is about to make a desperate situation worse: winter weather.
Winters in Europe can be extremely dire, especially in the Balkans, where thousands of migrants and refugees are currently passing through, trying to make their way to richer European countries like Germany and Sweden. And even if they manage to make their way to Germany, there is no guarantee they will get to stay somewhere warm.
The different countries and aid organizations' resources are already stretched to a breaking point and failing to find accommodation for the hundreds of thousands of refugees and migrants coming to Europe. A survey for the German newspaper Die Welt indicated that over 40,000 people are still living in tents in Germany.
The first snow of the season fell in Germany last week and the weather will only get worse from here. Aid groups also warn the weather will heighten the risk of conflict and disease, according to Reuters.
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When the weather was warmer, the migrants and refugees could walk around outside. Now they have to stay cramped inside their cold tents all day long with nothing to pass the time, which increases the risk of disputes among refugees and migrants.
Bilal, a refugee from Syria, told Reuters that fights, fueled by alcohol in some cases, are a already a daily occurrence in the camp of Celle in northern Germany. Many fights happen between migrants, who are coming into Europe searching for better economic opportunities - and will likely see their asylum claim rejected - and refugees, who are fleeing war and persecution and are almost guaranteed to have their asylum demand accepted.
Living in such close quarters also heightens the risk of diseases spreading rapidly. A doctor at the Celle camp told Reuters that two-thirds of the people at the camp have a cold.
In the Balkans, the situation is even worse. The cramped refugee camps, which consist of unheated tents, have been emptying over the last few weeks as authorities have organized themselves in order to keep the refugees moving toward western Europe.
However, with Hungary now closing its border with Croatia and other countries considering a similar move, the situation could quickly revert back to what it was like during the summer when overcrowded camps and closed borders created human bottlenecks and led to thousands of people sleeping outside without basic sanitation or access to water and food.
Reuters
"I am scared, everybody is scared," Ali Lolo, a Syrian refugee from Damascus, Lolo told The New York Times.
"We are worried they will close the border, but we are also worried about winter. We must get where we are going before the snows fall," added Lolo, who waited with his family last week beneath a tarp at an camp at the Serbo-Croatian border.
Too many to deal with
In Germany, everything available is used for accommodation, including sports halls and youth hostels, but the number of refugees and migrants is so high that there is not enough room to house everyone.
Even the refugees who have had their status approved are still staying in accommodation supposed to be for newcomers due to a housing shortage, Reuters reports.
In Celle, heaters pump warm air into the tents at a cost of 4,000 euros per day, but even that is not enough to keep the inside of the tents warm.
Reuters
German Chancellor Angela Merkel's popularity has sharply decreased over her handling of the refugee crisis. Meanwhile, anti-immigration far right parties are on the rise everywhere in Europe. On Saturday things took a turn for the worse, when a German politician was stabbed in the neck because of her pro-refugee stance.
As winter sets in, Merkel's "all refugees welcome" policy will need to weather its toughest test yet.
For one adviser who talked to Reuters, there is no doubt as to whether Germany can handle this new hurdle. "Absolutely, we can manage this," the adviser said. "But you can envision a worst case scenario where we have rioting over the winter. And that could shape the mood."