I don't know how the weather works though, but I like the way it works. It'd be bad if you'd get constant rain/snow just because you live in a certain area. Rain would render Tepig useless.
Well I do think that it could be over board, but then again the regions will only get biggeras gens progress and with the 3DS it could take a month to beat the game and explore everything. So maybe that week idea would work, but if you don't like the weather you can change it.
Sunny Day would make it sunny, melt snow and ice over time.
Hail would freeze ice and make slight amounts of snow/rain depending on the season.
Rain Dance would make lakes and ponds flood over a bit and make snow/rain depending on the season.
Defog/Cloud Nine/Air Lock would stop weather effects for a short while.
Maybe I'm think to much on this, but ideally I'd like massive open regions for gen 6.