Can i do a half marathon without any additional training?

A few days ago i saw an ad in a paper advertising a half marathon and it sounded fun. Sadly it was the next day and it as too late to sign up. That sparked an interest for me. I do 6-9 miles runs daily (with a few exceptions when time doesn't permit). Would i need to do any additional training before i participate in a half marathon or would be ok in my current state? (i'm 16 btw)