how can i say that there is rainy and sun

But isn't the use of "...il fait soleil" one of the phrases (the other being "Il fait du soleil.") that is incorrect and should be replaced (if you will) with "Il y a..." [+ noun] ? I think I read another answer from Cécile that uses the "Il fait... [+partitive +noun]. Is this a regional difference, or a formal/informal/colloquial  difference? I have told my students that -- even though examples can be found in multiple texts/guides in my classroom -- "Il fait du soleil.", "Il fait du vent.", etc are absolutely incorrect and sound "strange" to native French speakers. If they shouldn't be used, why are they given as possible answers by Kwiziq staff in this thread? Je ne comprends pas...