Save for a rainy day
例句：We save money for a rainy day.
It never rains but it pours
例句：I just got sacked and my wife left me！So it never rains but it pours！
right as rain
例句：I was sick，but now I feel as right as rain.
on cloud nine
例句：She passed the audition and now she is on cloud nine.
head in the cloud
例句：You can't always have your head in the cloud，you need to be down-to-earth.
例句：Chasing rainbows won't get you anywhere.
sail close to the wind
例句：If you believe what he said， you are sailing close to the wind.
know which way the wind blows
例句：He never tells his thoughts until he knows which way the wind blows.
be snowed down
例句：I've been snowed down by my work！
white as snow
例句：The accused didn't comitt the murder，he is as white as snow.
例句：A true friend is the one who shows up when you are in trouble, a fair-weather friend is the one who shows up when you are in happiness.