El Nino, La Nina and the Neutral Phases can show heterogeneous coincidence or influence in the increments or decreases in precipitation, presenting an association only in extreme cases. To determine possible differences, a 50-year analysis was carried out in two basins located in the two slopes of Mexico. To estimate increases and decreases, an average annual precipitation level was taken as the basis. The coincidences between the phenomena of extraordinary conditions and the precipitation, were observed in the Acaponeta River in 1992 with El Nino of a high MEI. In 1999 it coincided with La Nina of a high MEI with rainfall increase in both rivers. In 1983, there was a rainfall increase only for Acaponeta, and in 1992 it coincided with an increase in precipitation in both basins. Sometimes the El Nino rainfall coincided with some tropical cyclones. Rainfall increases were observed during the Neutral Phase of annual duration, as in 1961 in the Acaponeta River, and in 1984 in both rivers. All of the above indicates that El Nino is not exclusively associated with rainfall increases, can occur in La Nina and in the Neutral phase also, with or without tropical cyclones; Which makes predictability difficult on the basis of the associations with the mentioned phenomena. From the 1980s, tropical cyclones were more frequent during the Neutral Phases and considering the 50 years, in the presence of La Nina as well.