Don't make the classic girl mistake here and be worried that you can't marry the first guy you meet. Make the most out of it - it might suck at the end when you have to part, but you will have at least lived that experience.
Also, there is a very good probability that he is attracted to you in some way - the truth is, especially at that age, men find almost all women physically attractive in a way that women can't really understand.
Don't feel bad approaching him -
* its not unlikely to be the only time this happens to him in his whole life - if he is lucky or makes a lot of effort to get out there it might happen 3 or 4 times (its fine, we have to be men about these things) unless he is extremely attractive, in which case 10 or even 15 women might approach him during his entire life.
* you are both young - it takes longer for men to get into the whole 'dating thing' because unfortunately they have to make most of the effort (no offense, just cut him some slack is all i'm saying - he's probably never had any attention from girls and most if not all he has ever approached have rejected him - esp at 16)
* if it goes wrong you will be fine. just carry on as if nothing ever happened. its hard to believe but its a perfectly fine thing to tell a man you are attracted to him openly and its nothing to be embarrassed about for you if nothing comes out of it. men are nothing like women in this respect - be grateful for this. although i won't want to guess how your girl friends will be about it... if you are leaving in a month, then you have even less to lose.
* you don't want to regret this for the next week/month/year - have a stab at it.
* good luck. :)
Probably a bad idea.