J'espère que tu auras un bel automne.
Here's a breakdown of the translation:
* J'espère: I hope
* que: that
* tu: you
* auras: will have
* un bel automne: a beautiful fall
You can also use the more informal:
J'espère que tu vas bien pour l'automne.
This translates to:
* J'espère: I hope
* que: that
* tu vas bien: you are doing well
* pour l'automne: for the fall
The most accurate translation depends on the context and the level of formality you want to convey.