Rain causes several problems.

Water on the road surface reduces the traction of rubber tires. Water leaches oily substances out of the asphalt, floating to the surface to form a slippery film. Puddles obscure hidden obstacles in the road. Water on the front of the windshield reduces visibility. Condensation on the back of the windshield reduces visibility further. Colder temperatures reduces reaction time.

And I’m just talking about drivers in cars.

Cage drivers are my biggest fear when riding in rain, on busy roads in populated areas. Every time it rains in my area, some foolish driver will loose control and cause an accident. In normal, crowded highway conditions, other cars nearby smash up like bowling pins. Avoiding crazy car drivers should be the biker’s first concern.

Water in the form or rain causes similar problems for motorcyclists. You only have about 4 square inches of rubber traction to begin with, so you can’t afford to lose much due to rain. You can easily drive your tires past their limit for adhesion and traction. You know the result.

At 60 mph, fog or gently falling rain will get you wet. When exposed to wind, evaporating water will cool you off, which can be nice if you’re riding through a tropical shower. But If conditions are cold, then you’ll get cold too. Really cold, really fast.

If you have a windshield on your bike or faceshield on your helment, rain will obstruct your view of the road. Thick fog can stick like snow and give you a personal white-out right in front of your face. Cold rain on the face stings; rain in the eyes hurts.

Fog isn’t always sticky and wet, and can resemble low-level smoke. When riding into thick, dry fog, it’s easy to lose your bearings—like, “where’s the ground?”. Vertigo, and disaster can set in.