Nearly 1,600 firefighters were battling 20 fires Monday, with the country placed on alert from Saturday to Tuesday evening because of high temperatures and strong winds.

More than 500 have been battling the largest fire near Oliveira de Azemeis, south of the city of Porto, since Sunday.

Further to the south, at least two homes were burned in two villages in the Albergaria-a-Velha area, said mayor Antonio Loureiro.

"We already have houses in flames at the moment," he told Portuguese news agency Lusa.

Traffic has been halted on three motorways in the area, police said.

Drivers were told not to try to get to Aveiro. "That is the best way to not to put lives at risk," said mayor Vitor Ribero.

One firefighter died "suddenly" Sunday while taking a break from efforts to contain the fire, the interior ministry said Monday.

Portugal has seen less wildfires than usual so far this year. Some 10,300 hectares (25,500 acres) were lost to the flames by the end of August -- a third of what was destroyed last year and seven times less than the average over the last decade.

Lisbon has upped fire prevention funding ten-fold and doubled the budget to fight wildfires since deadly blazes in 2017 claimed hundreds of lives.

Scientists say human-caused fossil fuel emissions are increasing the length, frequency and intensity of global heatwaves, raising the risk of wildfires.

The Iberian peninsula is particularly vulnerable to global warming, with heatwaves and drought exposing the region to blazes.