I've never had a seasons expansion pack in any of the sim games I've played, but rain would be a really cool feature! Perhaps they could convert some regular puddles to mud puddles? My sims' kids and toddlers could go play in a mud puddle and get a special moodlet because it's so much fun! Hey, their parents would probably join in too because they're nature lovers! (maybe nature/childish teens and above could always do this, even past childhood). Your sims would visibly get covered in mud though (like dirt images already in the game) so they could wash up afterwards by taking a bath/shower.
This would fit in nicely with laundry stuff because your mud-covered clothes would need to be washed after playing outside!)
I would love this in my game!
