未雨绸缪

wèi yǔ chóu móu

lit. before it rains, bind around with silk (idiom, from Book of Songs 詩經|诗经); fig. to plan ahead

to prepare for a rainy day

wèi

not yet

rain

chóu

(light) silk

móu

used in 綢繆|绸缪[chou2 mou2]