It's called a rain suit. I got caught in a white-out downpour in East Texas but had dawned my rain gear beforehand. As a result of the downpour, there were vehicles in the ditches during the middle of summer. The traffic speed slows down so you are going to get wet no matter what shield you have.
Also had interment downpours in Illinois, Indiana, Kentucky and Tennessee on the same trip. Same solution, good rain gear.