True, I kinda wanted to see a rain spell that enhanced the food gain from farms/wheat/orchards.  Flood is possible though it sounds kinda like a bigger version of the Destroy Land or Lower Land spells, which we already have, though I'm sure you can't use those on cities.  Because if we could use a cheap terraforming spell to plunge an entire city block into the ocean, all other spells would very quickly lose their luster.  However, Flood was REALLY scary in Age of Wonders because it literally did cause ALL bodies of water to flood their banks, destroying all non-mountainous terrain in its path, and would even engulf whole cities if they didn't have a wall protecting them.  Weather spells would be an interesting touch, but they would no doubt have serious balancing issues.