Estimate of the upper limit of amplitude of Solar Cycle No. 23

AA* indices of values greater than 60 10(-9) Tesla are considered in order to characterize geomagnetic storms since the available series of these indi ces comprise the years from 1868 to 1998 (the longest existing interval of geomagnetic activity). By applying the precursor technique we have performe d an analysis of the storm periods and the solar activity, obtaining a good correlation between the number of storms (a) (characterized by the AA* ind ices) and the amplitudes of each solar cycle (zeta) and those of the next ( mu). Using the multiple regression method applied to alpha = A + B zeta + C mu, the constants are calculated and the values found are: A = 33 +/- 18, B = 0.74 +/- 0.13 and C = 0.56 +/- 0.13. The present statistical method indicates that the current solar cycle (numb er 23) would have an upper limit of 202 +/- 57 monthly mean sunspots. This value indicates that the solar activity would be high causing important eff ects on the Earth's environment.