On cloud nine.
飘飘然如上九重天。
 
Save for a rainy day.
未雨绸缪。
 
Fish bite best before a rain.
大鱼吃小鱼，天空要下雨。
 
For a morning rain leave not your trip.
不要因为早晨下了一场雨就不去旅行。 
 
Halo around the sun or moon ,rain or snowsoon. 
日晕三更雨，月晕午时风。
 
When ladybugs swarm,expect a day that’s warm.
蚂蚁搬家，天将雨。
 
Mountains in the morning. fountains in the evening.
早晨天上积雨云，晚上地下降暴雨。
 
When dew is on the grass,rain will never come to pass.
草上露珠闪，告别下雨天。
 
When the stars begin to huddle ,the earth will soon become a puddle.
月明星稀。