If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Saint-Jean-de-Sixt: The hottest months are usually July and August with an average temp of 58°F, while the coldest months are January and February with an average of 30°F. The snowiest months in Saint-Jean-de-Sixt are October, September, May, and December, with each month seeing an average of 5 inches of snowfall.