Rainy Day: Além de ser o dia chuvoso de hoje, it’s a time of (possible) (future) (financial) need or trouble.
Rain Check: an offer to renew or defer an unaccepted invitation or offer; a coupon, issued by a store to a customer, which guarantees that an item that is on sale at a reduced price but has been sold out may be purchased by that customer in the future at the lower price (nunca no Brasil!); the stub of a ticket to a ballgame or other outdoor event, entitling the holder to be admitted at a future date if the original event is rained out. Example: declined the invitation to dinner, but asked for a rain check. I can't come to dinner Tuesday but hope you'll give me a rain check.
Rains: A rainy season.
rain out: To force the cancellation or postponement of (an outdoor event) because of rain. Used in passive constructions: The ball game was rained out.
rain cats and dogs (Informal): To rain very heavily.
It's raining men, hallelujah... Isso já é outra história ... veja lyrics em:
Sources: Answers. com; Your Dictionary et al