I think my avatar is running low on suncream and I dont really want to get sun burn & my inner child would love to actually jump in some puddles from some rain. I think it would be kinda cool to have some areas at certain times to have rainfall and maybe in the artic snow falling, then to add even more fun maybe have some wind and fog around the varios wind turbines or maybe even sand storms. With all the rain and storms then maybe we could have IFN Umbrellas / Ponchos or Rain Related Clothing. And maybe even have an earthquake area I am guessing some people might not find this popular due to the take up in FPS to display these items but it would be kinda cool Also around ocean outlook would be nice to have a blow hole and maybe even an NPC guide to advise the times that the blow hole will activate.
They tried weather effects on Calypso in the past but it was soon removed because the lag it created was horrendous. If it could be done without the lag it would be cool, though it would be essential to also have an option for the player to switch it off in case of performance problems.
Toulan has several weathers effects in certain locations: snow, sandstorm, and rain. With ambient sound it adds a great sense of reality to the environment. Toulan isn't all that optimized yet, so general framerates are lower than on Ark, but I don't notice the weather effects decreasing FPS much. They're generated by the client, so they wouldn't cause any server lag, it would only be an additional task for the graphics card to deal with. Ark is the fastest FPS planet, so I think some tasteful weather effects would be fine. I wouldn't go much by what the Caly team has tried and failed... they don't seem all that skilled at (or interested in) bug fixing and optimizing.
If you want to check what Toulan has done, the areas where you see weather effects: Snow (Nahar city), sandstorm (anywhere in the desert), rain (near the PVP temple at the south of the map). They work best with accompanying sound (rain, howling wind, not sure if you can muffle all sounds when it snows but that might be cool).