Patron saints in viticulture (also known as "icemen" or in dialect as "ice-manders", in France Saints Glaces), or for the days from 12 to 15 May. On these days there are relatively often dreaded cold spells with frost (late frost) and snow in Central Europe. Before the end of this period, nothing is usually planted in the garden and no cattle are driven to pasture. In the past, fires were also common to ward off the cold. The fact is that in mid-May, after beautiful mild days, there are again strong cold air advances from the polar regions due to a high over Great Britain or Scandinavia. The air coming to Central Europe is then cold and dry and the daytime temperature hardly ever rises above 15 °Celsius. During the clear nights there is a particular danger of ground frost and freezing. Already flowering plants such as vines or trees can be severely damaged. From the middle of the month onwards, the probability of this weather situation decreases again.