High! If it rains hard and people are speeding or even doing the speed limit the tires of the car can plane .. actually come off the road. When wet, slow down! Of course if there is black ice or snow anyone knows it's safer to slow down. Fog ... no one needs to explain this one.
Perhaps you should come to the North country in Canada. Sometimes the roads have a mind of their own no matter how slow you are going. I do agree that the majority of accidents are caused by speed or not paying attention and cell phones aren't helping either.