CNN via Patricia De Melo Moreira/Getty Images

LISBON: A wildfire raging in northern Portugal amid scorching temperatures forced the evacuation on Saturday of a water park and the closure of a highway, firefighters said.

Over 70 firefighters backed by 21 vehicles were battling the blaze in scrubland near Vila Caiz, located about 55 kilometres northeast of Porto, the civil protection agency said.

Firefighters evacuated the Parque Aquatico de Amarante and closed a stretch of the A4 highway as a precaution, according to Commander Jose Pereira ? the head of the firefighters in the nearby town of Avintes.

"It was mainly because of the smoke," he told public television RTP adding it was not immediately clear how many people were in the water park at the time.

Portugal's national weather office placed 13 regions on a yellow alert ? the third highest level in a four-tier alert system ? on Saturday because of the heat.

Temperatures reached 38 degrees Celsius (100 Fahrenheit) in some southern areas.

After an uncommonly dry winter and spring, almost 79 percent of the Portuguese mainland was enduring extreme or severe drought at the end of July, according to the national weather office.

In June over 60 people were killed, and more than 250 were injured, in a giant wildfire at Pedrogao Grande in central Portugal that raged for five days.

Many of the victims were trapped in their cars by the flames.