There's a special seabreeze due to Ölands dry landscape and the proximity to mainland Sweden. This is most noticable in the spring when the water is cold and the land is warm, average wind is probably 20knts and almost always from the South.
From Kalmar, drive across the bridge to Öland. Turn south towards Färjestaden, 10km from the bridge you will see signs for Haga Park. It's one of the biggest camping grounds in Sweden so it will be hard to miss.
North of the windsurfers is a bird sanctuary that must be avoided. Check with the local windsurfing club for the rules, they are nice people and there are no fees. Kiting not allowed, go further about 1km south to Sandbergen.