G'day, I've kited a bit in the rain out at Scarborough in winter westerlies and don't have a problem as long as its strong enough so its still moving fast. The only problem you can have if its grey and fully overcast, there becomes a static field or something similar that will give you electric shocks. Read the post by Corey from last year when we were kiting Woodies in a very strong squally rainey day. I witnessed the sparks and crackling Corey received. Can be dangerous but still won't stop me though!
Read this:
www.seabreeze.com.au/forums/topic.asp?TOPIC_ID=7854