As I posted in another feature issue, this isn't about Stratis, it's about adding to the weather parameters in the editor, which can be used on any map. It would be nice, but it would involve re-texturing and maybe re-modelling every single tree, bush, flower and grass model in the game (well for temperate zones at least) to reflect seasonal changes, which is a lot of workload for somebody.
Upvoting because it would be a nice feature in the future, but more important things need to be done first.