I'm serious. Either I have terrible luck or WoW really does miss more often in weather. I just battled three or four people on Main all with a Rain or Sun team. Every time I used WoW, I missed. I tried, like, twice in all the battles.
The accuracy is the same in any weather, your unlucky :PP http://bulbapedia.bulbagarden.net/wiki/Will-O-Wisp_(move)
Thunder and Hurricane have lower accuracy in Sun or Sand, but higher in Rain.
