Hinteres Sonnwendjoch, Mountain summit in Thiersee, Austria

Hinteres Sonnwendjoch is a 1,986 m peak in the Austrian state of Tyrol and the highest mountain of the Mangfall range, part of the Bavarian Prealps. Its summit is built of main dolomite, with plattenkalk on the south side, and the mountain drops steeply to the north into the Grund. The privately run Ackernalm lies on its southern slope at about 1,400 m.

The summit is built of Hauptdolomit (main dolomite), with Plattenkalk limestone on its south side; the northern face drops steeply into the Grund. The massif belongs to the Mangfall range, a subdivision of the Bavarian Prealps, and at 1,986 m it is that range's highest point. The Brandenberg Alps immediately to the south are lower, which is why the peak gives wide views of the Central Alps.

The name Sonnwendjoch links the peak to the solstice (Sonnwende), though the sources record no documented solstice observatory. The summit lies in Tyrol, yet the standard southern approach starts at the privately run Ackernalm at about 1,400 m, reached by toll road from Bayrischzell or Kufstein. Hikers from Bavaria and Tyrol meet on the same paths.

The most common starting point is Ackernalm, reached by a toll road from either Bayrischzell or Kufstein. The trail crosses open terrain with steeper sections near the top, so sturdy footwear is recommended.

The summit consists of main dolomite, with plattenkalk on its south side. Because the Brandenberg Alps to the south are lower, the 1,986 m peak gives views of the Central Alps despite its modest height. The privately run Ackernalm lies at about 1,400 m on the southern slope.