Use your wipers and defroster as necessary for best vision. If the fog becomes so thick that you can barely see, pull completely off the road. Do not continue driving until you can see better. Turn off your lights or someone may see your taillights and drive into you. Drive more slowly because you cannot see as far.
Motorcycles are harder to see at night because most have only one taillight.
You will have less time to stop if a hazard lies ahead. Make sure you can stop within the distance lighted by your headlights. The law says you must turn your headlights on 30 minutes after sunset and leave them on until 30 minutes before sunrise. You must turn your lights on any time you can't see at least 1000 feet ahead. Use your low beam headlights whenever it is raining.