the heavens [open]

used to refer to the time when the sky opens up and it starts raining heavily

The idiom "the heavens open" originates from the concept of the heavens or sky opening up, symbolizing a sudden and heavy downpour of rain. The phrase is used metaphorically to represent the moment when the weather changes abruptly, and it starts raining heavily. In other words, it implies a dramatic and intense rainfall that seemingly pours from the sky.

We were walking home when the heavens opened, and we got completely drenched.
The forecast didn't mention rain, but suddenly, the heavens opened, catching everyone off guard.
As soon as we set up the tent, the heavens opened, and we had to scramble to keep our belongings dry.
We were enjoying the outdoor concert when the heavens opened, forcing everyone to seek shelter.
I forgot my umbrella, and of course, the heavens opened just as I stepped outside.

used to refer to the time when a situation suddenly improves

After weeks of studying, it was like the heavens opened up when he aced the exam.
When I finally understood the concept, it was like the heavens opened and the solution became clear.
When she realized she had won the lottery, it was like the heavens had opened and good fortune had rained down upon her.