On this page of the Forza Horizon 5 guide, you will find out if it is possible to change the season. In addition, you will learn how to check the current season.
Forza Horizon 5 is divided into four seasons. As in the case of changing the time of day, you can't change the current season.
Players are not able to change the season manually. It changes every week so waiting until the next week is the only way to change the season. By entering the Festival Playlist tab, you can see the current season (first tile on the left), and when a given season will end (yellow text on the right side of the menu).