Temperatures are dropping below zero these days at the end of February 2018, and they are doing so for a long time. How come?
Minus temperatures are not uncommon in the Swiss winter. What is rarer is that the weather in our westerly wind zone comes from the east for several days and that such a stable and strong bise situation and cold can set in.
Like every phenomenon, this one also has a cause: Sudden Stratospheric Warming.