Well, people may not think about it very much, but there's a pretty large air carrier airport just south-east of SFO. As long as your jet is a 777 or smaller, SJC is just fine as a divert. You might not be able to deplane (Customs), but you can wait out the weather on the ground. If the s**t really hits the fan at both SFO and OAK, then they suddenly notice SJC.