Wildfires blazing in central Chile have now killed at least 64 people and the toll will keep rising, President Gabriel Boric said on Sunday as the disaster left bodies in the streets and homes gutted.

Authorities warned of "complicated" conditions as they battled fires in the coastal tourist region of Valparaiso amid an intense summer heatwave, with temperatures soaring to 40 degrees Celsius over the weekend.

Rosana Avendano, a 63-year-old kitchen assistant, was away from home when the fire began to sweep through the city of Vina del Mar, where she lives with her husband.

"It was terrible because I couldn't get (to my house). The fire came here... we lost everything," Avendano said. "My husband was lying down and began to feel the heat of the fire coming and he ran away."

She feared the worst for hours, but eventually was able to contact her spouse.

"We can sadly confirm that there are 64 deaths," Boric said from Quilpue, outside the hard-hit city of Vina del Mar.

"The figure is going to rise. We know it is going to increase in a significant way," he added, saying it was the country's deadliest disaster since a 2010 earthquake and tsunami that killed 500 people.

Boric has declared a state of emergency, pledging government support to help people get back on their feet after he flew over the affected area in a helicopter on Saturday afternoon.

According to the national disaster service, SENAPRED, nearly 26,000 hectares acres had been burned across the central and southern regions by Sunday.

SENAPRED chief Alvaro Hormazabal said firefighters were battling 34 blazes as of Sunday morning, with 43 others under control.

Weather "conditions are going to continue to be complicated," Hormazabal said. (AFP)