There's no better place to celebrate Autumn, The exchange of the 4 seasons.
Going to your local autumn festival is all the delight with great seasonal foods for the specific timing. Eat everything pumpkin, enjoy the falling leaves, and find a great cornfield maze to explore and get lost in. Fall bring a new wind in, so you can leave a window cracked for night time and early morning breeze. It's fun and exciting to spook yourself for the month of October for Halloween by going to a haunted house.
For A lot of towns around the USA, and other worldly places; chili cook offs are a given.
Bring your pot of chili to your local chili fest. Even make up your own with a group of 20 or more to have a most amount of fun. Autumn is a good time just to take a jog or run the 5k race. The weather is perfect. And everyone's body temperatures are aware. Bringing a nice Autumn to enjoy.