Well, today it was 9 degrees (Celsius). You can't really expect any truly warm days until the end of May and even then it can be a crap shoot. We might get some 30 degree days in like July but usually not too many. You can expect maybe a few weeks of warm weather in the summer but it doesn't ever really get hot. (Unless you live in Southern Sweden and then you might get some longer stretches of warmth). Also consider a lot of days during the summer are cloudy, especially on the West coast. Overcast skies tend to make for milder days. If you're looking for days with lots of sun and warm weather you're not really going to get that in Sweden.

I have friends in Finland too, and they tend to have even cooler weather than we do in the summer, and their winters tend to be harsher as well.