I know this is an old thread - but I want to encourage everyone to race in the rain!
Why?
Cause it is a lot of fun! Does stuff break while racing in the rain? Yes - you bet, but stuff also breaks on a non-rainy days. I race both my touring car and rally car in the rain. Just make sure to pack your electronics in small ziplock bags, balloons and/or rubber gloves.
You'll have a blast drifting around corners and seeing you car throwing rooster tails of water (depending on body and car type) when running it on wet tarmac or dirt.
We are not in this hobby to save money... but to have fun!