The Mediterranean is 1000 miles or 1600 Kms long. The question that you ask is impossible to answer other than to say around Cyprus to Egypt reasonably warm but the rest is pot luck particularly at that time of the year and with the big variations in weather patterns at the moment even hazzarding a guess is so difficult. ..... Neil.
I apologisch that I was not more specifiek but I thought people will look up this cruise before they answer. The cruise is from Venice back to Barcelona.
As you live in Spain I would have thought you would have a better idea than us in the UK but just looking at Rome last November min 6 max 18 degrees was the average with little rainfall. Certainly sitting out on the deck sunbathing might not be a great idea at this time of the year as apart from lower temps you have the movment of the ship as well to take into consideration. We have sailed on the Millennium and the Infinity but not yet on the Summit but they are the same class of ship we had a great time and loved using the glass external lift.