Don´t know how the wind is there right now, however it would not tell you how the wind will be the next two weeks (check windfinder or similar)
Anyway June/July/August is the windy season for that area, so your chances should be pretty good. Well at least it always has been in my windsurfer days going to Guincho.
You will need a wetsuit, the water is pretty fresh even in summer. 3/2 mm steamer or with short arms recommended. Most surfers (who stay the whole time in the water) wear a thin full suit there even in summer.
On the other hand you are swedish so you might be a lot tougher concerning cold
But I would not take a risk.
You shoud also consider taking a small kite with you it might be howling.