Start a Grand Prix of at least 20% distance, weather set to "Heavy Rain". Change the difficulty to easy and the maximum amount of flashbacks to 4. Be aware, there are no mandatory pit stops in wet weather races. Try for consistency, as opposed to blistering speed. It is easy to spin in the wet, so it is better to be cautious. When turning, do not touch the throttle until you are facing out of the turn. The AI are very slow on the street circuits, so if you are confident in your ability to navigate tight turns, choose one of the following tracks:
If street circuits are not your forté, feel free to select your favorite track. Knowing the track well is essential, as visibility is severely reduced. With this in mind, do not drive directly behind other cars. The spray will make it near impossible to see.
Redbull, Mclaren or Ferrari are the best teams to choose from.