What you have to remember is, the weather temp given on this site is the temperature at Corfu airport, it is always that bit more hotter in Arillas, when we were there it was raining in Corfu Town and absolutely boiling in Arillas, so add a fair few degrees on top for what it will be like in Arillas.
As Sarah said, if you sit by the palm trees at The Bardis then you do get a slight breeze and also some shade if required. But in that heat if youre down the beach do get an umbrella, dont want anyone getting sunstroke, horrible!