Hmm... I don't want argue with you but please take a closer look. I've just checked the WEATHER file you provided with your mod. It's exactly the same as the original file. I think It proves my observations. We're unable to make any changes because game overwrites the settings to default values right before any battle. It's really strange - the game doesn't read the file at all. You can even delete it. The game will create new before the first battle.