Meteorological drought is an atmospheric condition characterized by a deficiency in the amount of precipitation and increased evapotranspiration. We calculated the magnitudes of average annual seasonal trends (June to September) of the following drought indicators for 1970-2011: average temperature (T avg), precipitation (Prec), potential evapotranspiration (PET), standardized precipitation evapotranspiration index (SPEI) on a 24-month scale (SPEI-24), and return periods (RP) of drought (SPEI-24). The indicators were calculated from records of daily T avg and Prec obtained from 38 CONAGUA (National Water Commission) weather stations located in the northern states of Sinaloa, Baja California Sur, Durango, Chihuahua, and Sonora. PET was calculated by the method of Thornthwaite; drought was calculated by the expression for SPEI-24 based on the calculation of deciles 1, 2, 3, 7, 8, and 9 of Prec; and the RP of SPEI-24 were calculated using the probability distribution function of Gumbel on time scales from 2 to 500 years. The nonparametric Mann-Kendall test was applied. The magnitude of change in the trends was estimated by Sen’s method for slopes. SPEI-24 showed positive and negative trends (-0.066 to 0.082). The results have predicted that there will be severe droughts in 2021 and 2036 in the states of Baja California Sur and Sinaloa.
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