@ReNNie Just made me think of something also. Corrupted save file. Try loading an older save & see if there is any difference?
Edit: Also, vanilla timecycle or have you modded your timcycle files (w_clouds.xml, w_clear.xml etc) or 'weather.xml' at all? Somehow, I presumed not but that question needs to be eliminated.
You might try pulling 'cfg.dat' & 'pc_settings.bin' out of where they are sitting (make backup, place somewhere else etc) & reloading the game (new ones will be created. Search for them on hard drive as Rockstar in all their wisdom have placed them in different locations depending on what version of GTA V you have. You'll find them in the same folder, usually where your save files are).