Do like they do in real restaurants. Remove the outdoor tables during winter.
...Thanks, I was about to rage-quit because sims were seated outside during a BLIZZARD.
It's a band-aid solution though. I'm still discontent and I do hope they will put some AI in there.
It is a venue in the middle of the forest, and for your information plenty of restaurants especially in small towns don't remove outdoor tables during winter, but merely stack the chairs upside down onto the tables until it is needed again. And some restaurants even have their outdoor furniture bolted to the ground.
