A wildfire burning out of control in Spain’s eastern province of Valencia has become one of the country’s biggest fires this year, and 35 aircraft were deployed to fight it as the blaze entered its fifth day, authorities said Friday.

The wildfire has already scorched more than 19,000 hectares (47,000 acres) along a 137-kilometer (85-mile) perimeter. Efforts to bring it under control Thursday failed and strong winds have made the fire “very aggressive,” the Valencian regional government said.

In neighboring Portugal, the government on Friday announced a nationwide three-day state of alert beginning Sunday. Portugal is in the grip of a severe drought and has also seen devastating wildfires this summer.

The measure, which grants authorities special, temporary powers such as barring people from woodlands, is a response to forecasts of inland temps above 40 degrees Celsius (104 degrees Fahrenheit) beginning Sunday in what could be the country’s third heat wave this summer.

Portuguese Interior Minister José Luís Carneiro said the armed forces would provide extra forest patrols on those days. He also announced that the Civil Protection Agency will get additional funding to hire another 500 firefighters.