Excellent example by Renen (posted in this forum):
So we've seen this thread a few times - and once we got to the point Yoshida said yeah but whose country would be base it off of? We dont want to do that kind of prejudice. (Or that they already have seasons in the form of permanent seasoned zones)
He also said expect nice weather and environment (so thats cool).
But this horse still hasnt been beaten enough. First suggestion to that issue is that servers are now regional - you could easily set each server's seasons to that regions seasons.
However the time length of each day isnt exactly the time length of each in game day so the reality is unless that matches up it really isnt possible to make game servers to real life servers. So why bother with that, lets make Eorzea have its own seasons could even go in pattern or in more unique complex stages like in the form of eras.
Like there are six elemental eras and each season could be based off those eras, so the six seasons of Eorzea. Though perhaps not in the order the eras came - so that you can attempt to align seasons with the holidays (an obvious NA one would be the winter festival within december).
Please feel free to suggest whatever weather or seasons, doesn't have to pertain to whatever I said. I really would just like to see an environment that has a persistence and change that feels breathing and alive.
Besides having seasons affect the general weather in zones visually you could have it pile with snow or slightly thaw out in "perma" frost areas. Or in streams you see fish climbing the streams, certain npc animals about (or not), could go into monsters but that is a "hardcore-ish" element that not everyone digs.
Also for weather please include wet effects on characters when it rains, or snow effects when it is snowy (shaders that apply a kind of snowy or wet film on players/rocks and such easy to touch up objects). Maybe a mask* to block out the raining effect under overhangings where water drips off. Even change the rate / depth of flora animations when it is extremely windy (trees leaves blowing really hard).
Some of this (zones changing through seasons) would have to be designed after release of ARR but nevertheless its something that would really be great to see.
*if you use a mask (besides the fact I have no idea how their rain is programed) you would then have to turn on an outside of the overhanging rain animation impervious to the mask so that it doesnt look like it suddenly stopped raining depending on camera angle.
For those that have no idea what I mean, I mean an invisible layer that when coming from a certain direction particular things are also invisible. A 3d mask would be required in this case. And the rain impervious to the mask placed at the overhanging is to ensure while within the mask all rain doesnt look like it stopped (looking from the inside out)