▁most ▁storm s ▁formed ▁during ▁the ▁passage ▁of ▁the ▁positive ▁Mad den – Jul ian ▁oscill ation ▁and ▁its ▁associated ▁upper - air ▁diver gence , ▁which ▁is ▁favor able ▁for ▁tropical ▁cy clone ▁formation . ▁Ext ended ▁repr ieves ▁in ▁tropical ▁activity ▁were ▁connected ▁to ▁upper - level ▁convergence . ▁Another ▁factor ▁that ▁led ▁to ▁a ▁below - aver age ▁season ▁was ▁the ▁presence ▁of ▁cool er ▁than ▁average ▁ocean ▁temper atures ▁during ▁the ▁peak ▁months , ▁helping ▁to ▁extend ▁the ▁period ▁of ▁less er ▁activity ▁that ▁began ▁throughout ▁the ▁eastern ▁Pacific ▁around ▁ 1 9 9 5 . ▁The ▁ 2 0 0 5 ▁became ▁a ▁record - ty ing ▁most ▁active ▁in ▁the ▁month ▁between ▁ 1 9 6 6 , ▁ 1 9 9 2 , ▁ 1 9 9 4 , ▁ 1 9 9 7 , ▁later ▁in ▁ 2 0 1 9 ▁forming ▁six ▁named ▁storm s ▁in ▁the ▁bas in ▁ ▁Systems ▁ ▁H urr icane ▁Ad rian ▁ ▁In ▁early ▁to ▁mid - May , ▁several ▁areas ▁of ▁dist urbed ▁weather ▁moving ▁west ward ▁from ▁Central ▁America ▁a ided ▁in ▁the ▁formation ▁of ▁a ▁broad ▁area ▁of ▁low ▁pressure ▁well ▁south ▁of ▁Mexico . ▁A ▁poor ly - defined ▁tropical ▁wave ▁became ▁inter tw ined ▁with ▁the ▁larger ▁system ▁over ▁subsequent ▁days , ▁leading ▁to ▁the ▁formation ▁of ▁a ▁tropical ▁de pression ▁at ▁ 1 8 : 0 0   UTC ▁on ▁May   1 7 . ▁The ▁nas cent ▁cy clone ▁intens ified