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

未

wèi

not yet

雨

yǔ

rain

绸

chóu

(light) silk

缪

móu

used in 綢繆|绸缪[chou2 mou2]