After finishing Lucy's final objective, she will reward you with the Rain theme. This theme is then automatically applied on your first station. If you wish to remove the theme, you can find the clear weather theme among the extensions in your storage: http://prntscr.com/794nje
Please click on the theme and the unwanted weather will be removed.
If you decide to use Rain again in the future, you will find it in Storage - Themes.
