NSW boy missing after family argument

A 15-year-old boy is missing in northern NSW after walking away from an argument with his family.

Daniel Johnson was last seen near the kiosk at Copeton Dam, south of Inverell, about midday on Sunday.

Police believe the teenager walked onto Copeton Dam Road and may be heading towards Dorrigo.

He is 155-160cm tall with brown hair and a sunburnt nose, and was wearing a grey Hurley T-shirt and blue shorts with white stripes.