Roads are dangerous at the start of a light rain when road oil and water mix to form a greasy film on the road.

Wet roads can be as dangerous as icy roads, so lower your driving speed in wet weather. You will need more distance to stop and you may skid on quick turns. Roads are more dangerous at the start of a light rain than they are after it has been raining for a while because the water forms a greasy film when mixed with oils on the road surface that have not yet washed away.