There is this stuff called "RainX"[1]. You apply it to your windshield and the rain beads off (hydrophobic). You can see really well even in heavy rain without wipers. (My dad used to use it on the family cars last century, and I still use it today).
It works great, though you have to reapply every few months when it wears off. And you can't apply it in the rain, so you have to remember ahead of time....