Modding weather

[-GandalfTheGrey]

Does anyone know how I could change the weather effects like rain or fog, or is it hardcoded ?
I mean changing how often they appear in battles and how dense they are.

 

[yehrom]

Nice question.
My request is a bit different,
I would like see a more global weahter, linked with the over-world.
Is it possible ?
Or is it actualy just a battle-map parameter ?