I have no objections to this, as long as the associated debuff doesn't make it entirely impossible to do anything lol. I mean it should be noticeable but it shouldn't be severe to the point where people just say "Oh there's a sandstorm? Not doing anything in Thanalan then." Sure it's more "realistic" but it detracts from playing the game, which is bad.

The only other con I can really think of is that in dungeons it would be completely nullified, unless some sort of artificial weather was created via magic or magitech means.