The answer is the riddle "Tomorrow will be sunny and the next day will turn cloudy"

There are no dark clouds in the sun, moon and sky, and it turns cloudy at night.

Guess: (sun, moon and sky) means (tomorrow) (cloudless) means (sunny weather); (Overnight) Tomorrow is in front, and overnight is (the day after tomorrow) (cloudy) That is (cloudy); It's sunny to cloudy ahead.