The wire connector for motor that connects to wiring harness plug if water got in the plugs wipers would do all kinds of crazy things.
It was necessary to unplug and dry out with hair dryer than apply di-electric grease on connections in plugs to help keep out moisture.
If you can tie plugs up as high as you can to keep away from upper hood opening.
You can also put rubber bulb weather strip across the hood opening.
Check out picture.