Which idiom is used to describe good weather and bad weather?

a bolt from the blue

[Interpretation] Thunderbolt: Thunder. It thundered on a sunny day. A metaphor for an unexpected and shocking event that suddenly happened.

[Source] Song Luyou's poem "Chickens don't crow for four nights": "Let Weng fall ill and suddenly get drunk. Just like for a long time, the sky is flying. "