a breeze : somthing easy for a person to do
eg: Because I studied English very well, the exam was a breeze

under the weather : sick
eg: Betra was feeling under the weather, so she didn't go to work

to break the ice : to begin a conversation with a stranger
eg: Cedric is very shy, If he goes to a party where he doesn't know anyone, he finds it hard to break the ice

come rain or shine : no matter how hard is it to do
eg: Uncle Jeremiah lives two hundred miles away, but he'll be at my birthday party come rain or shine

to save something for a rainy day : to prepare for trouble, usually by saving money
eg: Hanks makes only four hundred dollars a week, but every week he saves forty for a rainy day

to weather the storm : to wait and be patient until things get better
eg: Our business has had a lot of problems this year, But I'm sure things will be okay if we can weather thw storm for just more months

full of hot air : talking a lot but never doing what one says
eg: Many politicians are full of hot air. They make promises. but they don't keep them

to have one's head in the clouds : not to know or understand what is going on
eg: I don't think Celia understands that she is in danger of not passing the course. She seems to have her head in the clouds

to rain cats and dogs : to rain very hard
eg: It must be raining cats and dogs outside, The rain's poundind on the roof

snowed under : having a lot of work to do
eg: I have to stay late at the office tonight and finish some things because I'm snowed under with work

a fair-weather friend : a person who doesn't help when a friend is in trouble
eg: Judy showed that she was a fair-weather friend. When I needed help on my report, she refused