Brought up some good points here. Yes, weather and time will be consistent across the world. That is pretty standard within MMOs, though weather previously hasn't had any real effects so that might be a little trickier. People of any race should be able to read the storm, I would put it under Spirituality skills or Survival skills. Zulus might have a bonus to it as one of their racials. It would probably be set up as simple as: the computer has what the weather will be for the next 4 days, and you can look again with x% certainty y number of days. Miracles (like the Greek one in particular) will only affect within it's radius of say 1 mile…part of the cool effect of it. Miracles would replace the current weather for their duration without effecting future weather.
It's tough to say about weather on farming and building. My first thought is no, it will not effect building since building is carried out by NPCs and thus doesn't really matter how it's slowed. It would be awesome if I could have it affect both farming and tree growth, so that things like famines, droughts, and lumber shortages could occur. I don't think that would be too difficult systematically, just have the weather affect a global variable "tree growth" and "crop growth" within its radius.
