Don't ride in the rain if you can avoid it. It doesn't rain much in socal, so just wait for the sun to come out. But if you must, here some things to consider. 1. Lower the tire pressure in your tires. It will get you better traction on wet pavement. 2. Give yourself more time to stop, especially on hills! 3. Wear base layers, i.e. undershirt, cap, booties (if you have them). You're going to get soaked, but this will help somewhat with staying warm.

If it's raining before I start my ride, I won't go out. But if it's raining during my ride, I usually just suck it up and continue riding. Oh, also don't forget to lube your bike after the ride!

Be safe and have fun!!