August is the height of Mont Blanc's climbing season, where even in the warmest months fierce storms can strike quickly.
Several mountaineers have died already this summer, including at least one experienced guide, and local officials say they fear many people are coming to Mont Blanc ill-prepared for the dangers.
The group of five climbers and a guide were reported missing overnight when they failed to return to a refuge after a planned trip to the Aiguille d'Argentiere, which tops out around 12,800ft.
Mont Blanc, in addition to its primary peak, contains some 200 summits.
The bodies of five of the climbers were located yesterday, while a sixth has not been found, said Jean-Marc Peillex, mayor of Saint-Gervais, a town at the foot of Mont Blanc.
Search and rescue teams headed up the slopes in a window of calm weather.