A picture taken on June 18, 2017 shows the village of Campelo after a wildfire, from Figueiro dos Vinhos.
Guterres, in a statement issued on Sunday, condoled the Portuguese Government and people, saying he was "shocked and horrified" at the many lives claimed by the raging wildfires.
Secretary of State for the Interior Jorge Gomes said 62 people burned to death, mostly trapped in their cars engulfed by flames.
Several roads were cut off by flames and thick smoke as firefighters tried to prevent the flames from spreading.
Many victims were burnt as they were trapped in their cars around the epicentre of the blaze in Pedrogao Grande, in what is the deadliest such disaster in Portugal's recent history.
Photo A section of forest in flames on Sunday evening during a wildfire near the village of Mega Fundeira, Portugal.
Portugal's President, Marcelo Rebelo de Sousa, offered a word of comfort to those still battling the fires and said that "all that could be done was done". Every second vehicle on the roads is an ambulance, a fire engine or a police auto.
Three days national mourning was declared on the occasion that ends on Tuesday.
The two Britons who were injured in the fires also received treatment for smoke inhalation and have been discharged from hospital, according to The Portugal News.
"We escaped in time, me on the tractor and he with our van", Luisilda said.
"I am close to the dear people of Portugal, hit by a devastating fire which is raging in the forests around Pedrogao Grande, causing many victims and injuries", he said.
Devastating and deadly fires have been affecting central Portugal over the weekend trapping many drivers as the flames literally engulfed auto after vehicle. At least 59 people are reported to have been injured in the fire that erupted amid an intense heat wave and rainless thunderstorms. That left firefighters - backed by fire engines and bulldozers - to do the heavy work on the ground in temperatures that approached 40 degrees Celsius (104 Fahrenheit). There's a lot of forest around many small villages, and tragedy could strike again any time, any where, she said.
Police say lightning striking a tree may have caused the fire. "It is a real inferno, we have never seen anything like that", the mayor of Pedrogao Grande Valdemar Alves told reporters, adding that more than 20 villages had been affected. In response to the European Union's civil protection measure, Spain has sent in two dedicated firefighting aircraft to help control the blazes from the air.
About 60 forest fires broke out across the country during the night, with around 1,700 firefighters battling to put them out.
"Overwhelmed by the tragedy of Pedrogao Grande". Portugal's Social Welfare Department is providing social support for the displaced through 400 social welfare officials, assisted by the Portuguese Red Cross (see further details below).