Nebelberg is a municipality in the district of Rohrbach, in the Austrian state of Upper Austria. It is located in the northern part of the country, within the Mühlviertel region that borders the Czech Republic.
As a municipality, Nebelberg is one of the smaller administrative units in the Rohrbach district, which lies in the far north of Upper Austria. The area is characterised by the rolling granite hills and forested landscape typical of the Mühlviertel.