The city of Chillan, 400 kilometers (250 miles) south of Santiago, hit -9.3C, according to the Chilean Meteorological Directorate. "What happened this week in Chile and the Southern Cone in general is a cold wave caused by an escape of a polar air mass from Antarctica," climatologist Raul Cordero from the University of Santiago told AFP.Snow even fell in parts of the Atacama Desert, the world's driest, for the first time in a decade. "It is not so common for these cold air masses to extend so far north, so we cannot rule out that this is also caused by climate change," meteorologist Arnaldo Zuniga told AFP.The region expects relief in the coming days, with Buenos Aires reaching 12C on Thursday, Montevideo 14C and Santiago 24.7C. "I was quite surprised by the change from cold to hot — the change was very drastic," student Dafne Naranjo, 18, said in Santiago.Climatologist Cordero said heat waves have become more frequent than cold spells in recent years. "The frequency of heat waves has tripled, whether in summer or winter, not only in the Southern Cone but throughout the world," he said.