How long can the custodial parent leave their child unattended?

In the near future I'm going to have to fly back home for a few weeks to deal with some family matters, given school is just around the corner I don't think bringing my son with me is a very good idea. He's 16 and has all the skills I feel are necessary for him to do well without me, needless to say I feel he will do fine on his own. So I was wondering given my son's age is it legal for me to leave him at home without a guardian for an indefinite amount of time (anywhere between 3-6 weeks).