It was not in a port, but a few years ago when I was on a RCCL cruise, we were crossing the Med returning to Barcelona. The midday report from the captain was that it looked like clear sailing all the way in. I had an OV cabin overlooking the bow of the ship. About 2am the last night of the cruise, I was awakened hearing what sounded like water crashing over the bow and realized we were rocking and rolling. High winds (I turned the tv on to the navigation channel and while I don't remember the exact knots of the wind, I know it was super high) and rain and yes, waves crashing over the bow. I don't mind the rocking and rolling (other than pulling all the empty hangers off the rack), but a lot of people were very green at breakfast and waiting to disembark.
On researching, I found that that kind of pop up storm can happen in the middle of the Med with little to no warning.