How do I get weather-related spells?

[Ungod]

Bah! It's raining, but I want it sunny!

[Muratus del Mur]

Weather is set, unset, or changed, by using spells. you can get these from the wishshop in exchange for wishpoints. Wishpoints you can get only as reward for solving quests or during events. You can NOT buy wishpoints or trade them (in fact trading or facilitating obtaining wishpoints other than deserving them is forbidden and penalized).