At least 10 people have died and the blaze in the tourist region of Valparaiso has forced many to flee their homes.
“All forces are deployed in the fight against the forest fires,” President Gabriel Boric posted on X as he announced the measure, adding that emergency services would meet on Saturday to assess the situation.
The fires have ravaged thousands of hectares of forest since Friday, cloaking coastal cities in a dense fog of grey smoke and forcing people to flee their homes in the central regions of Vina del Mar and Valparaiso.
At least 10 people have died, according to a state representative of Valparaiso.
“We have winds of close to 40 or 50km [25-31 miles] per hour,” said Leonardo Moder, the director of Valparaiso’s national forestry corporation.
“This wind is hard because it carries lit leaves, branches or pieces of wood, and each creates a new little fire that grows into more fires,” he added.
The blaze is being driven by a summer heatwave and drought affecting the southern part of South America caused by the El Nino weather phenomenon, as scientists warn that a warming planet has increased the risk of natural disasters such as intense heat and fires.
In the towns of Estrella and Navidad, southwest of the capital, the fires have burned nearly 30 homes and forced evacuations near the surfing resort of Pichilemu.
“I’ve never seen anything like it,” 63-year-old Yvonne Guzman told the AFP news agency. When the flames started to close in on her home in Quilpue, she fled with her elderly mother, only to find themselves trapped in traffic for hours.
“It’s very distressing because we’ve evacuated the house but we can’t move forward. There are all these people trying to get out and who can’t move,” she said.
About 7,000 hectares (17,300 acres) have already been burned in Valparaiso alone, according to CONAF, the Chilean national forest authority, which called the blazes “extreme”.
Images filmed by trapped motorists have gone viral online, showing mountains in flames at the end of the famous Route 68, a road used by thousands of tourists to get to the Pacific coast beaches.
On Friday, authorities closed the road, which links Valparaiso to the capital, Santiago, as a huge mushroom cloud of smoke “reduced visibility”.
As Chile and Colombia battle rising temperatures, the heatwave is also threatening to sweep over Argentina, Paraguay and Brazil in the coming days.