Everything Under the Moon

Okay, I know that my reply is months late, but I did some Google-ling and it seems Hades and Persephone are associated with Autumn. This is representative of her beginning her half year stay in the underworld. More info about it can be found here https://suite101.com/a/fall-autumnal-eq ... th-a388742

I personally associate the Green Man with the fall or autum. I think this is because part of his role is protector of the animals and the fall here is mainly hunting season. You could also focus on the God or spirits of the hunt. The fall is a time of the last harvest and gathering of meats and nuts.

Veles was the Slavic God of autumn, often associated with death, dragons, and magic. He was something of a trickster as well, almost akin to Loki in the Norse pantheon. He had a festival that lasted from late December to February, the Veija Noc (The Great Night). He was also considered a god of nature.

Jack Frost comes to mind.
Mabon Festival re Child of Promise.
Annual migrations like insects, bats, deer, Bears, birds & especially geese & the N.American "SnowBird" migration to Florida.