Spoke with Yoshida about current lack of a weather effect toggle. Currently, there really isn’t any meaning to the weather that occurs randomly within the realm of Eorzea, however, in the future plan on making weather a much more meaningful event and as such do not plan on implementing a toggle.
Thank you for getting a response to my thread, though the response is kind of underwhelming. I like the fact that more things in-game will be tied to elements and weather, but this puts a lot of stress on my PC. I know XI had a lot of things tied into weather, and it had a toggle. I just figured it would be an easy fix for a lot of people to see improved performance on lower-end (hell, mid-grade) PCs, myself included.

(btw, this is the only modern game my PC has any trouble playing at all. This includes Bioshock 2, Crysis 2, The Witcher 2, etc)