How do you describe the sentence of weather change?

1, it was sunny and white clouds when I got off work yesterday, but today the weather has changed, and now there is no sign at all.

2, the weather has changed, the rain has been falling, I don't want to go out, I slept all morning.

The weather has changed, and I am dead. The Yellow River is not yellow.

4, the weather has changed ... look at the off-duty time, just ask for leave with the leader. Say, I'll go for a while, the weather has changed, and I'm afraid of rain ... Is the leader still happy? .