What is the meaning of the title of the novel, The Art of Racing in the Rain?

Rain on the track is one of the biggest weather-related
challenges a race car driver will face. According to this story, the protagonist, Denny
Swift, was one of the best race car drivers under rainy conditions. He knew how to
handle the car on the wet tracks without losing control or losing speed. This fact is
used as a metaphor throughout the story. Off the track, Denny is challenged by some very
emotional issues, which could be considered similar to rain on a race track. His wife
died, his child was taken away, and he was accused of raping a minor. Under these types
of pressures, other people might have been wiped out, just as some race car drivers
might have been wiped out on a rainy track during a race. However, Denny knew how to
control his emotions, just as he knew how to control his car on a wet
track.