I think something shitty has happened to the singer and he's asking if you feel how he feels by saying
"I wanna know, have you ever seen the rain? Coming down on a sunny day"
Meaning that even though the day is perfect, it's still shit to him and people keep telling him "it's going to be okay."
(The last sentence, which he finished with a comma instead of a period is just the same thing he stated in the first sentence.)
So, in English, Silencer commented:
I think something shitty has happened to the singer and he's asking if you feel how he feels by saying "I wanna know, have you ever seen the rain? Coming down on a sunny day" Meaning that even though the day is perfect, it's still shit to him and people keep telling him "it's going to be okay." (The last sentence, which he finished with a comma instead of a period is just the same thing he stated in the first sentence.)