▁the ▁summer ▁which ▁move ▁east ▁in ▁a ▁clock wise ▁motion ▁across ▁the ▁western ▁United ▁States ▁bringing ▁mon so onal ▁mo ist ure ▁to ▁the ▁area . ▁This ▁will ▁usually ▁occur ▁during ▁the ▁summer ▁months ▁( us ually ▁in ▁July – Se ptember ). ▁Snow ▁is ▁extremely ▁rare ▁in ▁the ▁Gre ater ▁Los ▁Angeles ▁area ▁and ▁bas in , ▁but ▁the ▁nearby ▁San ▁Gabriel ▁Mountains ▁and ▁San ▁Bernard ino ▁Mountains ▁typically ▁receive ▁a ▁heavy ▁amount ▁of ▁snow ▁every ▁winter ▁season . ▁The ▁greatest ▁snow fall ▁recorded ▁in ▁dow nt own ▁Los ▁Angeles ▁was ▁ ▁on ▁January ▁ 1 5 , ▁ 1 9 3 2 . ▁ ▁El ▁Ni ño – S ou thern ▁O sc ill ation ▁Histor ically - spe aking , ▁the ▁warm - phase ▁of ▁an ▁El ▁Ni ño – S ou thern ▁O sc ill ation ▁( EN SO ) ▁regime ▁typically ▁coinc ides ▁with ▁above ▁average ▁precip itation ▁across ▁Southern ▁California . ▁The ▁above ▁average ▁sea - sur face ▁temper atures ▁in ▁the ▁equ atorial ▁Pacific ▁Ocean ▁are ▁largely ▁responsible ▁for ▁this ▁as ▁the ▁ocean ▁acts ▁as ▁a ▁rich ▁mo ist ure ▁source ▁for ▁tropical ▁mo ist ure ▁to ▁ad ve ct ▁towards ▁the ▁North ▁American ▁continent ▁in ▁atmos pher ic ▁river ▁events . ▁Prior ▁to ▁the ▁strong ▁El ▁N ino ▁of ▁ 2 0 1 5 – 2 0 1 6 , ▁the ▁previous ▁two ▁strong ▁El ▁Ni ño ▁events ▁in ▁ 1 9 8 2 – 8 3 ▁and ▁ 1 9 9 7 – 9