The prediction of solar activity is one of the most challenging topics among the various Space Weather and Space Climate issues. In the last decades, the constant enhancement of Space Climate data allowed to improve the comprehension of the related physical phenomena and the statistical bases for prediction algorithms. For this purpose, we used geomagnetic indices to provide a pow erful algorithm (see Diego et al 2010) for the solar activity prediction, based on the evaluation of the recurrence rate in the geomagnetic activity. The aim of this paper is to present the validation of our algorithm over solar cycle n. 24, for which a successful prediction was made, and upgrade it to forecast the shape and time as well as the amplitude of the upcoming cycle n. 25. Contrary to the consensus, we predict it to be quite high, with a maximum sunspot number of 205 ± 29, that should be reached in the first half of 2023. This prediction is consistent with the scenario in which the long-term Gleissberg cycle has reached its minimum in cycle n. 24 and the rising phase is beginning.
Long term evolution of geomagnetic activity under the influence of 11 year cyclic variations in solar activity during solar cycle 23 and 24