How does a world conquest map have anything to do with the weather?
The world conquest map is an interesting idea, but it does take away from the 'anywhere, anytime' feeling that Multiwinia has now. Making a world map would mean pigeon-holing the scope of the war and the strength of the various factions. Leaving it dubious pleases the playerbase since they can assume their favorite color is winning, loosing, or whatever.
Weather, in terms of cyclones, 'snow', lightning and volcanoes and such, I think would be neat to have on a given map. In the setup one can select a specific weather condition, 'random', or none, and have to fight in those conditions. Then again, it would take away from the character of some maps (Like Scorched Earth, which is defined by the random blasts of lightning frying some MWs).