It's not just dependent on weather. It is a FATE chain that's spaced 2 hours or so apart. You have to complete the first two FATEs (Long Live the Coeurl and Coeurls Chase Boys) for the final one (Coeurls Chase Boys Chase Coeurls) to appear.

So yeah, unless you're in that zone gathering for hours or really really want those spotted glamour gear, it's not worth camping.