After a bit of work I finally did it to make an DataPack, that contains a Weatherchanger! When you hold the Item it will change the weather (Rightclick).The crafting recipe is very expensive, but you have to imagine, what you can do with this item! This is for example very good, if you want to fly with an Riptide III Trident. Have fun ; )

Command to get the item: /function weatherchanger:giveitem