You will need to look in assetto corsa/content/cfg for the weatherfx folder and see if it lists the weather such as sol_02_FewClouds is in the directory and named exactly the same. If it is try verifying the integrity of your steam files: https://support.steampowered.com/kb_article.php?ref=2037-QEUH-3335
This can sometimes fix errors when MODS have been loaded.
I am away from my PC until tonight but will look and send you some screenshots to help if you've not resolved it
I've change the name for the few clouds folder and it worked, from sol_02_few_clouds to sol_02_FewClouds. Thanks a lot. Really enjoyed the mod as I learn how to drive the car and also learn about the tracks. Thank you for helping out