The presented work focuses on wind energy production in Germany and the corresponding day-ahead forecast errors. The installed wind energy in Germany is unequally distributed, with most wind power installed in the northern lowlands. Fig. 1(a) shows the spatial distribution of installed onshore wind energy in 2014 (from Ref. [29], therein Figure 12) and in Fig. 1(b) the control areas of the four German TSOs Amprion, TransnetBW, TenneT and 50 Hertz are depicted. In the area of TransnetBW, the least amount of wind energy production capacity is installed. The TSO's focus lies on balancing demand and supply as accurately as possible. All arising discrepancies need to be compensated. In order to compute day-ahead wind power forecast errors, the so-called Meta-forecasts (best possible forecast of the four German TSOs) are used. These forecasts provide the basis for the day-ahead processes (system operation and marketing) and are published on the TSO's web pages ([30], [31], [32] and [33]) together with an estimation of the actual power production. The power forecast and production values have a temporal resolution of 15 min and are the basis for all further investigations. The time period between 2012 and 2014 is considered.