I just got seasons, so I haven't yet experienced ruined events from weather yet. I have had sims get stuck at festivals though. My solution is to edit or replace the community lots so that they have all of the essentials for traveling sims. Usually Planet Honey Pop gets replaced with a mall. I found a nice on in the gallery that had beds and a kitchen on the top tier of the mall. It looked like how a department store would set up displays, it was really nice. My sims can sleep through a festival in comfort. ;)