While safe and dangerous are two relative terms since riding a bike carries a certain degree of risk, it is safe to say that riding your motorcycle when it’s raining involves a few elements that increase this risk. Even if you use the best rain riding gear, the roads get wet and thus more slippery and visibility and tire traction are reduced, which affects your safety.
To decrease the risk of a crash, it is thus best to use motorcycle tires that provide a good grip even in wet conditions, a helmet with an antifog screen as well as a rain jacket and rain pants that are brightly colored so other people can see you with greater ease.