Evaluation of the SIDC forecast and numerical models to predict a geomagnetic storm with K of at least 5, across the years. Top panel: POD (lines, left vertical axis, Eq. (5)) and HSS (bars, right vertical axis, Eq. (10)). Middle panel: PC (lines, left vertical axis, Eq. (6)) and the TSS (bars, right vertical axis, Eq. (11)). POD and PC are shown for all forecasts, while HSS and TSS only for the SIDC forecast. Bottom panel: the proportion of days with an event, a hit, a miss and a false alarm (on a logarithmic scale). The proportion of hits and the proportion of misses sum up to the proportion of events. Note that some or all verification measures cannot be calculated and are left undefined in case of lack of events or hits (e.g. year 2009).