The only thing we can say is that Hebridean weather is dramatically changeable! The old adage definitely holds true, the weather just IS, it’s just getting the right clothes so that your explorations are not restricted.
This means a full waterproof outfit, which can be just a light shell in the summer and sturdy walking boots. A hat, shorts, tee-shirts and sunscreen as sun burn can happen on Iona.
Another must in summer is some form of insect repellent to protect yourself from the wee highland beastie....’the midge’. They are at their worst from June until September on Mull and Iona but luckily with the almost constant breeze on the island they are rarely a problem.
A small back pack to carry water-proofs, picnics and a small thermos that we can fill for you is also very useful.