Chile's forest fires have been raging for weeks. What caused them?

Chile's forest fires have been raging for weeks. What caused them?
By Ricardo Martínez
February 10, 2017
Public Radio International

"It started with a burst of flames in the steep Chilean hillsides of Valparaíso, two days after crowds celebrated New Year’s. Then flames started popping up farther south. Since then, almost 100 fires have burned hundreds of thousands of acres across the country."