According to this report, the German government is encouraging its citizens to stockpile emergency supplies of food, water, and cash:
http://deutsche-wirtschafts-nachrichten.de/2016/08/21/bundesregierung-buerger-sollen-lebensmittel-und-bargeld-bunkern/ [translation required]
What do they know that we don't? Is it war, or a financial crash they are most worried about?
Note well the US government is not warning its citizens about anything. In my view, this is not because they believe nothing bad will happen, but because they really do not give a damn about us.