Dont take too much notice of the weather forecasts, it was predicting rain when we went in May and it was bloomin hot all week!!
The weather forecast is always for Corfu Town anyway and the weather in Arillas is always a bit different, you are an hour away from Corfu Town and you might not think it makes much of a difference but it does.
In May it was bucketing down in Corfu Town, the streets were flooding etc and in Arillas it was about 38-40 degrees!
I reckon you will have glorious sunshine all week, if it does rain its normally a quick shower and then its sunshine time again, so fear not, your holiday wont be ruined!!