英汉词典

1. （时期、季节等）多雨的
    During a rainy day, season, or period it rains a lot.

    e.g. They walked along the promenade on a rainy night...
           他们在一个雨夜沿着海滨道散步。
    e.g. The rainy season in the Andes normally starts in December.
           安第斯山区的雨季通常在12月份来临。

2. 以备不时之需;未雨绸缪
    If you say that you are saving something, especially money, for a rainy day, you mean that you are saving it until a time in the future when you might need it.

    e.g. I'll put the rest in the bank for a rainy day.
           我要把余款存入银行以备不时之需。