Try cleaning the wipers and glass with some rubbing alcohol, 99% stuff if you can find it. Should get rid of any residue that's on there.

 

I'll deal with the wipers and see what happens. But should that no longer be there if I had cleaned the windshield with all manner of cleaners and clay bar and wiped dry with MF towels? The water follows the pattern of the wipers so they definitely affect it, but you can see even in the second picture that the residual moisture remains where the wipers don't touch the windshield as well even after wiping dry with the MF.

 

Okay. Before I got a chance to deal with it, we got rain this week. That coating thing isn't happening now . Well, at least it's gone and the windshield is how it should be.

 

Try cleaner wiper bLades with window cleaner or rubbing alcohol