Colle San Carlo is a high mountain pass at an elevation of 1.951m (6,400ft) above the sea level, located in the Aosta Valley region of north-western Italy.
The summit belongs to the Graian Alps, a mountain range in the western part of the Alps, in Italy. The road to reach the summit is asphalted. It’s called Strada Regionale 39 (SR39). Open to traffic throughout the year, may be closed for short periods in winter when the weather is bad. The road to the top is steadily steep. Near the top there are often a lot of flies.
This pass has been climbed several times in Giro d’Italia race. There are 2 routes to reach the summit. Starting from La Thuile, the ascent is 7 km long. Over this distance, the elevation gain is 530 meters. The average percentage is 7.6 %. And starting from Morgex, the ascent is 10.5 km long. Over this distance, the elevation gain is 1.049 meters. The average percentage is 10 %, but includes sections over 13%.