There are always a number of Harvest/October festivals. Can't afford them all, but I do try one or the other. I once lived in crawling distance to the Munich Oktoberfest grounds. That was an adventure, meeting people from all over the world.
Otherwise, the favorite activity is enjoying cooler, dryer air, and maybe harvesting some of my own patio peppers and tomatoes.
There is one festival I really want to see some year: Celtic Colors on Cape Breton Island, Nova Scotia. Maybe when retirement kicks in. Then I 'd be able to say I visited Canada, too 😎