All of these are good suggestions, but more importantly - RELAX! All this nonsense about a steel frame suddenly rusting away to nothing if it gets breathed on wrong is just that - nonsense! How many rusty cars do you see on the road around you? How many rusty bikes? Not many, I would guess. Riding occasionally in the rain in San Mateo won't hurt your bike one little bit. Don't worry about it. If the bike is ridden and left outside year-round in, say, Detroit - then yeah, you might want to take special precautions. In San Mateo? Nah......