There’s a commonsense law that when you need windshield wipers — when visibility is 1,000 feet or less — you should also turn on headlamps. This law is often ignored, and many people don’t realize they can be ticketed for noncompliance.
Some newer cars have headlights that turn on automatically when there is moisture on the windshield, as well as when it gets dark.
Notice how much easier it is to see an oncoming vehicle, as well as the vehicle you are following, when its lights are on during rain or snow. We should all want to provide the same increased visibility of our own vehicle during wet conditions. This affords everyone greater safety.