User blog comment:YowAnime/Weather Manipulation/@comment-30281369-20200815024126

The Emperors abilities to incite natural disasters (except Shanks who hadn't displayed such ability) is thanks to their Devil Fruit; meaning that it's not a trait unique to being an Emperor. That said, the whole change in clouds was a result of Shanks and Whitebeard's clash of Haoshoku Haki which caused the sky to split, the same happened during Kaido's and Big Mom's confrontation and again in a battle with Gol D.Roger against Whitebeard.