Usually its just the same as any other time in Icmeler, but I usually take a cardie or two, and then buy a couple of pashmina's, just incase the tops of your arms or shoulders get a little chilly.
Usually I dont need to wear a cardie or anything, but last year was an exception to the weather, I was blooming freezing most of the time, wearing jeans, body warmers etc, but hopefully it will be back to normal this year.
You might experience an occassional thunderstorm or two, but they usually pass quickly and make fantastic viewing