Once you arrive by car in Santa Caterina Valfurva, in the province of Sondrio, continue driving to the Rifugio Forni parking lot along the valley of the same name.

Do not forget to buy the pass at the automatic issuing machine at La Fonte in Santa Caterina, You can also find it at the tourist office and in some bars-restaurants in the village, as well as in the Stella Alpina and Forni Refuges.

The ascent to Pizzo Tresero, a good 3,594 m high, begins by crossing the small wooden bridge over the Frodolfo Torrent, then follow the signs for the Glaciological Trail and, continuing eastward, go up the valley keeping to the right, you will thus find yourself at the foot of an obvious gully, which descends from the slope to the right. Its entrance is almost opposite the Branca Shelter, climb up the wide depression and, about halfway up, you are on the Forni Glacier, continue until you exit the gully, with the slope softening and opening up into a large amphitheater, this area serves as a base for ascents to San Matteo, Tresero and Cima San Giacomo.

Continue further to the right, with the trail beginning to pick up gradient again, thus reaching the shoulder that connects from Pizzo Tresero to Cima San Giacomo, here the gradients reduce again, but shortly afterwards they become challenging again. We deviate to the left ascending in the direction of Punta Pedranzini, at the base of the latter a last steep section begins, leading to the ridge of the southeast ridge that connects to Pizzo Tresero.

With good snowfall it can be done with skis on your feet, otherwise it is advisable to hang up the skis to your backpack and put on crampons, a few minutes and you are at the summit. For the descent, you have to consider the snow conditions, if you decide to follow the same route as the ascent, watch out for the first part of the ridge where some rocks may surface. There is no shortage of alternatives, along the couloirs that are encountered both before and after Cima San Giacomo, but it is better to inquire from the refuges.