Portugal has been forced to ask for international help, as it is still trying to recover from its deadliest fire on record in June, which killed 64.
A state of emergency has been declared in almost half of the country, north of the Tagus river.
At least 36 people died in Portugal at the weekend and more than 50 were injured.
Three people died in Spain’s Galicia region – two of them women found inside a burnt-out car, the third a man in his 70s, was killed as he tried to save his farm animals.
Most of the fires in Galicia were started by arsonists, the head of the region Alberto Nunez Feijoo said in a radio interview.
Spain’s Interior Minister Juan Ignacio Zoido said some of those responsible had already been identified and face up to 20 years in jail if convicted.
At least one person was arrested in Portugal for allegedly starting a fire.