And suddenly the sky is cloudy again. I'm telling you that next chapter besides the reveal about the D, the chapter will end with a clash between Luffy and Kaidou and the clouds splitting in 2 like the clashes with Shiro vs Shanks and Linkin vs Kaidou.
When this arc started I thought that it was just a possibility but I discarded this because when Nekomamushi transformed he said that the sky was clear, but now Kaidou is moving Onigashima and the sky is cloudy once again before chapter 1000, there is no way Oda don't do this