 An unusually warm winter , with warm days and cold nights , was also a factor . Water in the mountain 's fissures froze and <unk> repeatedly , further weakening the mountain 's supports . Heavy snowfall in the region in March was followed by a warm April , causing the mountain <unk> to melt into the fissures . GSC geologists concluded that the weather conditions that night likely triggered the slide . The crew of the freight train that arrived at Frank shortly before the disaster said it was the coldest night of the winter , with overnight temperatures falling below − 18 ° C ( 0 ° F ) . Geologists speculated that the cold snap and rapid freezing resulted in expansion of the fissures , causing the limestone to break off and tumble down the mountain . 
