I had to do a house call on a Saturday, so figured that I'd take the trust Honda CB500F for a spin since it was not only a beautiful spring day, but also a great bit of road to get there. Sorry about the helmet whistle.
Overall the bike is good in the rain, but the bike itself only plays a small part in how it is in the rain. Being a naked bike, the lack of wind protection does mean you get more wet if you get caught in a sudden shower without a rain jacket on. The tyres play a big part in how the bike is in the rain. I've only done a few rides in the rain but I've found the Michelin Road 5 tyres are very good in the wet. The lower power of the bike helps too. The first time I got caught in the rain I wanted to test the grip, so from a rolling start (of about 20kmh/12mph) I gave it full throttle in first gear and there was no noticeable wheel spin. I've not tested the front grip level as I don't want to drop it. I've not ridden in heavy rain though.
Yeah the weather there is pretty different to where I am in Australia. We can get pretty heavy rain when it storms though. We will often get up to 50mm of rain in an hour from a spring or summer storm. We once had 350mm of rain in 5 hours here. That caused some pretty serious flash flooding (although not as bad as the actual flooding we get)