The music is new yes. (technically it is from a old update) but the weather is not. It is not "Merged" with the other effects it happens just as the boat. We would have needed a update to actually add "new" weather ala comet showers, and dalamud weather.

So I'll say it again the weather isn't new. Nothing new was added to the game for the final update aside from the music.

I should also point out if turning weather effects on or off is not as easy as flipping a switch (changing a few lines of code to enable or disable) then something is terribly wrong with the games code.