Do you think they'll introduce some type of weather in the jungle adventure gp?

don't think so

I highly doubt it...

If they do plan on adding in seasons eventually, then why should they focus on rain now instead of "when" the Seasons pack comes out? Then they can fine tune each world to what they deem Seasons to affect (ie. Oasis Springs or Selvadora (or whatever you call it) probably shouldn't have snow).