Can I cast a fireball while blinded? Yes.
— Jeremy Crawford (@JeremyECrawford) October 4, 2017
How do you “point your finger to a point you choose within range” if you can’t see that point? You point towards it and specify a distance. "That way, 50 feet" *fwoosh*
— Dan Dillon 👥 (@Dan_Dillon_1) July 23, 2019
How do you know you’re not 10 feet from a wall if you are blind? If you can’t see a “point” I don’t know how you aim to the point. This caught my eye because I recently played with a DM who cast fog cloud on our party and the battlefield and ruled it foiled our fireball plans. I guess to your point, though, the text of the spell does not indicate “a point YOU CAN SEE” like some other spells do.
— DM Dad (@HoosMartin) July 23, 2019
Correct, it doesn't and that's quite deliberate.
To speak to your wall point, check out "A Clear Path to the Target" (PHB pg 204). If you accidentally try to shoot a fireball through a wall right in front of you… kablooey!
— Dan Dillon 👥 (@Dan_Dillon_1) July 23, 2019