"Rain"
One who only appears when times are good.
To set aside a resource for when it's really needed.
Sick.
Under the weather
Reschedule.
Rain check/cheque
Extremely happy.
On Cloud 9
Take the attention away from another person.
Steal someone's thunder
Whatever happens.
Come rain or shine
Not paying attention.
Head in the clouds
Things can be very quiet, before they get very chaotic.
Things seem to happen all at once.
When it rains, it pours
There is something good in everything.
Every cloud has a silver lining
Confused.
In a fog