Yeah generally people here in the UK have to go for a hardy/tough strain when growing outdoors, especially so in the North of England and Scotland Growers in the south have it a bit easier so for sure weather is a big factor.
I'd say if I lived some place like Spain I'd be doing loads of balcony/outdoor grows and would back myself to do good grows with that kind of climate to work with. But the great thing with outdoors is the yield you can get. I have seen people do grow diaries where they get a years supply(and that is smoking daily a nice amount) from the single grow, with some left over if they want to sell a bit on to m8's.
Good soil perp seems to be another thing which all the best grows outdoors feature. basically you have to put more work in, but you can get very well rewarded ! And you have of course f-all in your house/apartment so it's safer, just make sure you find a good spot where no-one will find it as I have also seen peeps hard work get robbed at the last minute, what a sick feeling that must be.