When riding on wet roads during a storm, the most dangerous time to do so is immediately after the storm starts. Water and oil don’t mix and there are oil deposits on every road that you ride on.
When it rains, those oil deposits become oil slicks. You shouldn’t have to be told that an oil slick is dangerous. If you hit an oil slick on your motorcycle, chances are that you’re going down. So, do yourself a favor, if it’s just started storming, try to wait a few minutes before you get on your bike.