We were on a Med cruise last October and weather was generally very pleasant.
On the day we were to dock in Livorno the port was closed for awhile because of high winds, however.
When we did dock some or all of the tours to Florence were cancelled. A tablemate , who had not been to Florence before, made it in and back and had a wonderful time on his own.
But weather is always an unknown, no matter when you go.
We prefer spring and fall where crowds are somewhat less and chances of high heat and humidity are lower.