Damp conditions are not uncommon in the Bay.  Getting some vapor over the wing during a climb out would not be a surprise. Getting it on the approach can also happen but not so often.  A FedEx MD-11 was on the approach to Oakland while I was walking along the shore.  As it headed away, they were configured for the final approach as some flashes of vapor showed themselves above the wing.  I happened to get them this time.