Unlike most sports, there is no formal "running season". Track, cross country, marathons, obstacle course races, 5ks, ultras... they happen all the time, every weekend, all year long the world over.
Beyond that if you were to ask runners from around the world what their favorite season to run in was you'd get a myriad of different answers (some determined by their home's climate no doubt).
Some people love the New Year. That time in January and February where you capitalize on the cliche "New Year Resolution" and carry (or begin) the momentum of New. New start, new plan, new life, new year, new beginning.
For others the perfect running season is spring. The sun is out, the snow is melting, and there's the glory of that perfect light misting rain (running in the rain automatically increases your hardcoreness 10x... in case you didn't know).
Droves come out to run in the summer. The sun is out, the showers have mostly dried up, and (for many) the heat invigorates. Shorts get shorter, shirts come off, and the primal sweat that gives instant feedback to your hard work, sacrifice, and dedication is... abundant.
All of those seasons have their merits. They're also all wrong. You see, there is no weather to run in quite like fall. Additionally, if you are so blessed to live in God's country (East Tennessee), than Fall is even more wonderful.
The humidity retreats, the air is light and crisp, the breeze is magical, and the temperature is... perfect.
It's impossible to walk outside on a crisp fall morning in Tennessee and not be overcome with the _need_ to take off and run. Run from your problems, sprint away your stress, leave your haters behind, and just run from it all.
Meditation in motion.