Dave R has it right. I was once inbound to Cork (as flight crew) when fog prevented us from landing. After holding for an hour, with no improvement, we diverted to Shannon where we offloaded all the pax onto buses. I was just settling down with a coffee for a long wait when ops phoned to say the Cork weather had improved and could we please get over there pronto. Well it's not a long flight in a 737, so we landed in a cavok Cork long before our pax got there...