Weather changes were not planned for a20, but after noticing the state of the code, that it was not gold quality, I ended up spending a lot of December overhauling it. The overhaul is basically done, but the simulation parameters are still being tweaked and needs testing/feedback. Now the players reaction to the weather is completely separate, so this does not change what happens to the player being hot/cold/wet/etc.
The amount of logic we already run from xml adds a good amount of overhead to the game. It could be added, but it would be slow, so not likely.