Rain gear, definately.
I've ridden about an hour at a time in the rain here quite a bit. I have a Sympatex lined riding suit, so I'm covered for weather and general highway speed/touring riding conditions. Pretty hot in the summers out here, though. My leather jacket and First Gear riding pants with rain liner are good for about an hour in the rain. Elkskin gloves are okay. Eventually they get soaked, but I haven't much liked rain covers on my hands. A cheapo (~ $40-$80) rain suit usually stores easily and does the job when needed. You might find a fisherman's rain suit at a yard sale. Bulky, but very easy to get in and out of.
I think a windshield helps a bit too, though not really necessary. I have a simple handle-bar mounted windshield on my Honda, and sport windscreen on the Triumph. Both seem to redirect some of the stuff that otherwise would be on me. For the rain, I like the bigger screen on the Honda.
BTW, make sure you have good tires and brakes for the rain. If you don't already, slow down a bit and ride conservatively. Our brakes don't work in the rain like in dry; and even the best tires don't have the same traction, especially when the rain is just starting and brings up all the oil on the surface. I put new tires on recently, and it vastly improved my handling in the rain and dry.
